MeasAPI

Super class for measurement algorithms for LabExT.

Aside from being an "interface" for measurement algorithm code, this class offers some basic functionality for executing measurements. It holds the currently set measurement parameters and the selected instruments (description and pointers to driver instances).

To get a running measurement, change the properties: name and settings_path. You need to specify the requested instrument types in get_wanted_instrument and a set of default parameters in get_default_parameter. The measurement algorithm needs to be implemented in the algorithm method. See their respective reference below. For a How-To on implementing a new measurement algorithm, see the New Measurement Algorithm page.

Attributes:

Name	Type	Description
check_param	str	Class attribute. Will affect what the measure function does on missing parameters: 'Raise' Raises an exception, 'Debug' Generates a log entry (This will most likely lead to an exception in the algorithm), 'Auto' Fills the missing parameter with its default value.
check_instr	str	Class attribute. Will affect what the measure function does on missing instruments: 'Raise' Raises and exception, 'Debug' Generates a log entry (This will most likely lead to an exception in the algorithm), 'Ignore' Do Nothing
name	str	Name of the measurement, typically similar of equal to the class name.
settings_path	str	File name of the settings file of this measurement, can be anything and should end in '.json'.
selected_instruments	dict	Set by the LabExT GUI after instrument selection stage. Keys is an instrument type, values is one instrument description dictionary from instruments.config (i.e. a VISA address, a driver class name, channel information and optionally some more constructor arguments for the driver).

Source code in LabExT/Measurements/MeasAPI/Measurement.py

class Measurement:
    """Super class for measurement algorithms for LabExT.

    Aside from being an "interface" for measurement algorithm code, this class offers some basic functionality for
    executing measurements. It holds the currently set measurement parameters and the selected instruments (description
    and pointers to driver instances).

    To get a running measurement, change the properties: `name` and `settings_path`. You need to specify the requested
    instrument types in `get_wanted_instrument` and a set of default parameters in `get_default_parameter`.
    The measurement algorithm needs to be implemented in the `algorithm` method. See their respective reference below.
    For a How-To on implementing a new measurement algorithm, see
    [the New Measurement Algorithm page](./code_new_meas_example.md).

    Attributes:
        check_param (str): Class attribute. Will affect what the measure function does on missing
            parameters: `'Raise'` Raises an exception, `'Debug'` Generates a log entry (This will most likely lead to an
            exception in the algorithm),  `'Auto'` Fills the missing parameter with its default value.
        check_instr (str): Class attribute. Will affect what the measure function does on missing instruments:
            `'Raise'` Raises and exception, `'Debug'` Generates a log entry (This will most likely lead to an exception
            in the algorithm), `'Ignore'` Do Nothing
        name (str): Name of the measurement, typically similar of equal to the class name.
        settings_path (str): File name of the settings file of this measurement, can be anything and should end in
            '.json'.
        selected_instruments (dict): Set by the LabExT GUI after instrument selection stage. Keys is an instrument type,
            values is one instrument description dictionary from instruments.config (i.e. a VISA address, a driver
            class name, channel information and optionally some more constructor arguments for the driver).
    """

    check_param = 'Raise'
    check_instr = 'Raise'

    def __init__(self, 
                 experiment: Optional[StandardExperiment] = None, 
                 experiment_manager: Optional[ExperimentManager] = None):
        """Constructor of a measurement.

        The arguments are automatically filled when using the measurement with the LabExT GUI. For standalone use, the
        arguments do not need to be provided.

        Arguments:
            experiment (LabExT.Experiments.StandardExperiment): Reference to the experiment instance. Optional, but can
                be used to enable live-plotting during measurements.
            experiment_manager (LabExT.ExperimentManager): Ref to the main experiment manager of LabExT, the root
                object which interconnects all parts of LabExT. Used to access all loaded instruments. Optional for
                stand-alone usage outside the LabExT GUI.
        """
        self._experiment = experiment
        self._experiment_manager = experiment_manager

        """
        Measurement attributes, to be overridden by subclass.
        --> FILL THESE PARAMETERS IN YOUR SUBCLASS!
        """
        self.name = 'ExampleMeasurementName'
        self.settings_path = 'example_meas_save_file_name.json'

        """
        Measurement class internal use
        """

        self.selected_instruments: Dict[str, Dict] = {}
        """Dict of strings of instrument roles as defined in instruments.config"""

        self._parameters: Dict[str, MeasParam] = {}
        """Dict of measurement parameters, values are MeasParam() instances"""

        self._instruments: Dict[Tuple[str, str], Instrument] = {}
        """Dict for initialized instruments, format: (role_name, instr_class_name): instr_object"""

        self._instr_pointer = None
        """Only used internally in class Measurement"""

        self.wanted_instruments: List[str] = []
        """List of strings of instrument types as defined in instruments.config"""

        self.logger = logging.getLogger()
        """Logger object, use this to log to console and log file"""

        self._id: uuid.UUID = uuid.uuid4()
        """A random id for the measurement. It is based on the measurement name and the parameters."""

    @property
    def id(self) -> uuid.UUID:
        """Returns a unique ID for this measurement based on its name and its parameters.

        Measurements with the same name and parameters will have the same id.
        """
        return self._id

    @property
    def parameters(self) -> Dict[str, MeasParam]:
        """`dict` of `MeasParam`: access the currently set parameters for this measurement. If no parameters were set,
        the default parameters are taken. Key is the parameters name and the Value is a `MeasParam` instance.
        """
        if self._parameters == {}:
            self._parameters = self.get_default_parameter()
        return self._parameters

    @parameters.setter
    def parameters(self, new_param):
        self._parameters = new_param

    @property
    def instruments(self) -> Dict[Tuple[str, str], Instrument]:
        """`dict` of `Instrument`: Holds the instances of the instrument drivers after calling `init_instruments()`,
        otherwise returns an empty dict. Keys are a 2-tuple of strings: (type, driver name): type is the type
        requested in `get_wanted_instrument()` and the driver name is the class name of the instruments driver. The
        values are pointers to initialized instrument drivers.
        """
        return self._instruments

    @instruments.setter
    def instruments(self, new_intrs: Dict[Tuple[str, str], Instrument]):
        self._instruments = new_intrs

    def get_name_with_id(self) -> str:
        """Returns the measurements `name` property and the unique id for this measurement's instance.
        """
        return str(self.name) + " (shortened id = " + self.id.hex[-5:] + ")"

    def init_instruments(self):
        """Instantiates instrument drivers according to `self.selected_instruments` and saves them in `self.instruments`

        This method gets called from the LabExT GUI and does not need to be invoked by the user.

        Raises:
            RuntimeError: In case any instrument could not be initilized. Sometimes initialization fails silently...
        """
        for instr_class in self.get_wanted_instrument():
            self._experiment_manager.instrument_api.create_instrument_obj(instr_class,
                                                                          self.selected_instruments,
                                                                          self.instruments)
        # check that all instruments were correctly initialized, if this is not the case, we raise an Exception
        if not all(inst is not None for inst in self.instruments.values()):
            raise RuntimeError('Instruments were not initialized correctly.')

    def get_instrument(self, instrument_type: str) -> Instrument:
        """Returns the pointer to the initialized instrument for the given instrument type.

        Use this function within self.algorithm() to get the pointer to the instrument driver you can use for
        instrument interaction.

        Arguments:
            instrument_type (str): The type string of the instrument requested.
                Must be in the list specified in `get_wanted_instrument.()`.

        Raises:
            ValueError: If the instrument with the given type cannot be found in the dict of the initialized
                instruments.
            RuntimeError: If the instrument with the given type is not initialized yet.

        Returns:
            Instrument: Initialised instrument driver.
        """
        for (itype, _), instr in self.instruments.items():
            if itype == instrument_type:
                if instr is not None:
                    return instr
                else:
                    raise RuntimeError("Instrument with type " + str(instrument_type) + " not initialized.")
        else:
            raise ValueError("No instrument with type " + str(instrument_type) + " in dict of initialized instruments.")

    def _get_data_from_all_instruments(self) -> Dict[str, Dict]:
        """Gets the settings of all instruments used in the measurement.

        Called from a standard experiment routine from LabExT to save all involved instrument's meta data and settings.
        """
        inst_data = {}

        for cat, i in self.instruments.items():
            self.logger.debug("getting params from: " + str(cat) + " actual class: " + str(i.__class__.__name__))
            inst_data[cat[0]] = i.get_instrument_parameter()

        return inst_data

    @staticmethod
    def get_default_parameter() -> Dict[str, MeasParam]:
        """The dictionary of all parameters required in this measurement at their default value.

        Inside the `algorithm`, you can access all parameters via the `parameters` argument which is the same
        structured dictionary as specified here but with the parameter values as chosen in the GUI.

        This method must be overriden for any working measurement implementation. See
        [the New Measurement Algorithm page](./code_new_meas_example.md).

        Returns:
            dict: keys are parameter names (strings), its values are instances of `MeasParam` or any of its
                subclasses

        """
        raise NotImplementedError()

    @staticmethod
    def get_non_sweepable_parameters() -> Dict[str, MeasParam]:
        """A `dict` mapping names of the parameters that are explicitly non-sweepable to the corresponding `MeasParam`.

        If all parameters are sweepable this method should return an empty `dict`.
        The default implementation also returns an empty `dict`.

        Returns:
            dict[str, MeasParam]: names of the parameters that aren't sweepable mapped to the corresponding parameters
        """
        return dict()

    @staticmethod
    def get_wanted_instrument() -> List[str]:
        """The list of all instrument types (strings) required in this measurement.

        Inside the `algorithm`, you can access the instantiated instrument driver classes by accessing the
        `instruments` argument which is a dict. The list you return in this method will be the keys of said dict.

        If you want to use more than one instrument of the same type, you can add a number after the instrument type.
        So to include two lasers and one power meter, I would return: `['Laser 1', 'Laser 2', 'PowerMeter']`.

        This method must be overriden for any working measurement implementation. See
        [the New Measurement Algorithm page](./code_new_meas_example.md).

        Returns:
            list: the elements are strings of instrument types as available in instruments.config
        """
        raise NotImplementedError()

    #
    # Measurement Routine and Helper Functions
    #

    def measure(self, device, data, **kwargs):
        """Gathers the parameters and instruments set via GUI and executes `self.algorithm()` with correct arguments.

        First checks whether all the needed contents are present, and if so starts execution of the algorithm. This
        function can take some optional arguments, namely parameters and instruments, to override the already saved
        ones.

        Furthermore, there are modes in place to fill missing parameters automatically. The flags check_instr and
        check_param can take various (static) values, that will dictate how measurement will handle missing parameters
        and instruments.

        There should be no need for a sub-class to overwrite this method.

        Arguments:
            device (Device): Device instance on which the measurement is performed. Allows to adapt measurement
                algorithm according to some device property.
            data (dict): Dictionary in which we store the result of the measurement.
            **kwargs: `'instruments'` An optional dict of instrument drivers. `'parameters'` An optional dict of
                some parameters. Can be filled partially!

        Raises:
            ValueError: If some instrument or parameter is missing and the check_ flags are set to `'Raise'`.
        """
        # update the attributes of measurement class, if allowed
        allowed_keys = {"parameters", "instruments"}
        self.__dict__.update((k, v) for k, v in kwargs.items() if k in allowed_keys)

        # check instruments
        for i in self.get_wanted_instrument():
            for (itype, _), instr in self.instruments.items():
                if itype == i:
                    if instr is not None:
                        break
                    else:
                        if type(self).check_instr == 'Debug':
                            self.logger.warning("Instrument " + i + " not initialized.")
                        elif type(self).check_param == 'Raise':
                            raise ValueError("Instrument not initialized: " + i)
            else:
                if type(self).check_instr == 'Debug':
                    self.logger.warning("Instrument " + i + " not found.")
                elif type(self).check_param == 'Raise':
                    raise ValueError("Instrument not found: " + i)

        # remove class name from key, s.t. the algorithm method has direct access via the names:
        instr_dict_no_classnames = {k: v for (k, _), v in self.instruments.items()}

        # check parameters
        for k, v in self.get_default_parameter().items():
            if k not in self._parameters:
                if type(self).check_param == 'Debug':
                    self.logger.warning("Did not find parameter " + k)
                elif type(self).check_param == 'Auto':
                    self._parameters[k] = v
                elif type(self).check_param == 'Raise':
                    raise ValueError("Parameter not found: " + k)

        return self.algorithm(device, data, instr_dict_no_classnames, self.parameters)

    def algorithm(self, device, data, instruments, parameters):
        """The main body of the measurement algorithm to be performed.

        Generally includes the following steps:
            1. read all parameters to variables
            2. read all instrument driver instances to local variables
            3. do preliminary checks, e.g. if the desired parameters are possible with the selected instruments
            4. save the used parameters in the `data['measurement settings']` dictionary
            5. set instrument settings according to chosen parameters
            6. execute the measurement routine
            7. read back data from the instruments and store it in the `data['values']` dictionary
            8. (recommended) check if you have populated all fields in the `data` dictionary by using
                `self._check_data(data)`

        This method must be overriden for any working measurement implementation. See
        [the New Measurement Algorithm page](./code_new_meas_example.md).

        Arguments:
            device (Device): Device instance on which the measurement is performed. Allows to adapt measurement
                algorithm according to some device property.
            data (dict): Dictionary in which we store the result of the measurement.
            instruments (dict): Dictionary with the instr. types as keys and the instrument driver instances as values.
            parameters (dict): Dictionary of all parameters. Keys are parameters names, values are `MeasParam`
                instances.
        """
        raise NotImplementedError

    @classmethod
    def setup_return_dict(cls) -> Dict[str, Dict]:
        """Gives the absolute bare minimum of keys which need to be filled in `data` dictionary in an `algorithm()` run.

        Returns:
            dict: The minimum set of keys for a `data` dictionary necessary to populate during a call of `algorithm()`.
        """
        data = {'measurement settings': {}, 'values': {}}
        return data

    def _check_data(self, data):
        """Checks if all necessary fields are present in the `data` dict.

        Use this method at the very end of an `algorithm()` implementation to check if you did not forget to fill any
        important field in the `data` dictionary.

        Prints a warning to the log if a mandatory key is present but does not contain any data.

        Arguments:
            data (dict):  Dictionary with data to be tested on completeness.

        Raises:
            ValueError: If a mandatory key is not present.
        """
        if 'values' not in data:
            raise ValueError(
                "Data Error - No value specified in data['values']")
        if not isinstance(data['values'], dict):
            raise TypeError(
                "Data Error - data['values'] is not of type dict.")
        if len(data['values']) == 0:
            self.logger.warning(
                "Data Warning for measurement {:s} - data['values'] dict is empty.".format(self.name)
            )
        if 'measurement settings' not in data:
            raise ValueError(
                "Data Error - No value specified in data['measurement settings']")
        if not isinstance(data['measurement settings'], dict):
            raise TypeError(
                "Data Error - data['measurement settings'] is not of type dict.")
        if len(data['measurement settings']) == 0:
            self.logger.warning(
                "Data Warning for measurement {:s} - data['measurement settings'] dict is empty.".format(self.name)
            )

    #
    # Side Window open function
    #

    def open_side_windows(self):
        """Include any code you want to be executed on the "open side windows" button for the measurement.
        """
        self.logger.warning('There are no side windows defined but open_side_windows() was called.')

    def store_new_param(self, new_params):
        """Used as callback function for the GUI to set parameters of the measurement.
        """
        self.parameters = new_params

id: uuid.UUID property

Returns a unique ID for this measurement based on its name and its parameters.

Measurements with the same name and parameters will have the same id.

instruments: Dict[Tuple[str, str], Instrument] property writable

dict of Instrument: Holds the instances of the instrument drivers after calling init_instruments(), otherwise returns an empty dict. Keys are a 2-tuple of strings: (type, driver name): type is the type requested in get_wanted_instrument() and the driver name is the class name of the instruments driver. The values are pointers to initialized instrument drivers.

logger = logging.getLogger() instance-attribute

Logger object, use this to log to console and log file

parameters: Dict[str, MeasParam] property writable

dict of MeasParam: access the currently set parameters for this measurement. If no parameters were set, the default parameters are taken. Key is the parameters name and the Value is a MeasParam instance.

selected_instruments: Dict[str, Dict] = {} instance-attribute

Dict of strings of instrument roles as defined in instruments.config

settings_path = 'example_meas_save_file_name.json' instance-attribute

Measurement class internal use

wanted_instruments: List[str] = [] instance-attribute

List of strings of instrument types as defined in instruments.config

__init__(experiment=None, experiment_manager=None)

Constructor of a measurement.

The arguments are automatically filled when using the measurement with the LabExT GUI. For standalone use, the arguments do not need to be provided.

Parameters:

Name	Type	Description	Default
experiment	StandardExperiment	Reference to the experiment instance. Optional, but can be used to enable live-plotting during measurements.	None
experiment_manager	ExperimentManager	Ref to the main experiment manager of LabExT, the root object which interconnects all parts of LabExT. Used to access all loaded instruments. Optional for stand-alone usage outside the LabExT GUI.	None

Source code in LabExT/Measurements/MeasAPI/Measurement.py

def __init__(self, 
             experiment: Optional[StandardExperiment] = None, 
             experiment_manager: Optional[ExperimentManager] = None):
    """Constructor of a measurement.

    The arguments are automatically filled when using the measurement with the LabExT GUI. For standalone use, the
    arguments do not need to be provided.

    Arguments:
        experiment (LabExT.Experiments.StandardExperiment): Reference to the experiment instance. Optional, but can
            be used to enable live-plotting during measurements.
        experiment_manager (LabExT.ExperimentManager): Ref to the main experiment manager of LabExT, the root
            object which interconnects all parts of LabExT. Used to access all loaded instruments. Optional for
            stand-alone usage outside the LabExT GUI.
    """
    self._experiment = experiment
    self._experiment_manager = experiment_manager

    """
    Measurement attributes, to be overridden by subclass.
    --> FILL THESE PARAMETERS IN YOUR SUBCLASS!
    """
    self.name = 'ExampleMeasurementName'
    self.settings_path = 'example_meas_save_file_name.json'

    """
    Measurement class internal use
    """

    self.selected_instruments: Dict[str, Dict] = {}
    """Dict of strings of instrument roles as defined in instruments.config"""

    self._parameters: Dict[str, MeasParam] = {}
    """Dict of measurement parameters, values are MeasParam() instances"""

    self._instruments: Dict[Tuple[str, str], Instrument] = {}
    """Dict for initialized instruments, format: (role_name, instr_class_name): instr_object"""

    self._instr_pointer = None
    """Only used internally in class Measurement"""

    self.wanted_instruments: List[str] = []
    """List of strings of instrument types as defined in instruments.config"""

    self.logger = logging.getLogger()
    """Logger object, use this to log to console and log file"""

    self._id: uuid.UUID = uuid.uuid4()
    """A random id for the measurement. It is based on the measurement name and the parameters."""

algorithm(device, data, instruments, parameters)

The main body of the measurement algorithm to be performed.

Generally includes the following steps

1. read all parameters to variables
2. read all instrument driver instances to local variables
3. do preliminary checks, e.g. if the desired parameters are possible with the selected instruments
4. save the used parameters in the data['measurement settings'] dictionary
5. set instrument settings according to chosen parameters
6. execute the measurement routine
7. read back data from the instruments and store it in the data['values'] dictionary
8. (recommended) check if you have populated all fields in the data dictionary by using self._check_data(data)

This method must be overriden for any working measurement implementation. See the New Measurement Algorithm page.

Parameters:

Name	Type	Description	Default
device	Device	Device instance on which the measurement is performed. Allows to adapt measurement algorithm according to some device property.	required
data	dict	Dictionary in which we store the result of the measurement.	required
instruments	dict	Dictionary with the instr. types as keys and the instrument driver instances as values.	required
parameters	dict	Dictionary of all parameters. Keys are parameters names, values are MeasParam instances.	required

Source code in LabExT/Measurements/MeasAPI/Measurement.py

def algorithm(self, device, data, instruments, parameters):
    """The main body of the measurement algorithm to be performed.

    Generally includes the following steps:
        1. read all parameters to variables
        2. read all instrument driver instances to local variables
        3. do preliminary checks, e.g. if the desired parameters are possible with the selected instruments
        4. save the used parameters in the `data['measurement settings']` dictionary
        5. set instrument settings according to chosen parameters
        6. execute the measurement routine
        7. read back data from the instruments and store it in the `data['values']` dictionary
        8. (recommended) check if you have populated all fields in the `data` dictionary by using
            `self._check_data(data)`

    This method must be overriden for any working measurement implementation. See
    [the New Measurement Algorithm page](./code_new_meas_example.md).

    Arguments:
        device (Device): Device instance on which the measurement is performed. Allows to adapt measurement
            algorithm according to some device property.
        data (dict): Dictionary in which we store the result of the measurement.
        instruments (dict): Dictionary with the instr. types as keys and the instrument driver instances as values.
        parameters (dict): Dictionary of all parameters. Keys are parameters names, values are `MeasParam`
            instances.
    """
    raise NotImplementedError

get_default_parameter() staticmethod

The dictionary of all parameters required in this measurement at their default value.

Inside the algorithm, you can access all parameters via the parameters argument which is the same structured dictionary as specified here but with the parameter values as chosen in the GUI.

This method must be overriden for any working measurement implementation. See the New Measurement Algorithm page.

Returns:

Name	Type	Description
dict	Dict[str, MeasParam]	keys are parameter names (strings), its values are instances of MeasParam or any of its subclasses

Source code in LabExT/Measurements/MeasAPI/Measurement.py

@staticmethod
def get_default_parameter() -> Dict[str, MeasParam]:
    """The dictionary of all parameters required in this measurement at their default value.

    Inside the `algorithm`, you can access all parameters via the `parameters` argument which is the same
    structured dictionary as specified here but with the parameter values as chosen in the GUI.

    This method must be overriden for any working measurement implementation. See
    [the New Measurement Algorithm page](./code_new_meas_example.md).

    Returns:
        dict: keys are parameter names (strings), its values are instances of `MeasParam` or any of its
            subclasses

    """
    raise NotImplementedError()

get_instrument(instrument_type)

Returns the pointer to the initialized instrument for the given instrument type.

Use this function within self.algorithm() to get the pointer to the instrument driver you can use for instrument interaction.

Parameters:

Name	Type	Description	Default
instrument_type	str	The type string of the instrument requested. Must be in the list specified in get_wanted_instrument.().	required

Raises:

Type	Description
ValueError	If the instrument with the given type cannot be found in the dict of the initialized instruments.
RuntimeError	If the instrument with the given type is not initialized yet.

Returns:

Name	Type	Description
Instrument	Instrument	Initialised instrument driver.

Source code in LabExT/Measurements/MeasAPI/Measurement.py

def get_instrument(self, instrument_type: str) -> Instrument:
    """Returns the pointer to the initialized instrument for the given instrument type.

    Use this function within self.algorithm() to get the pointer to the instrument driver you can use for
    instrument interaction.

    Arguments:
        instrument_type (str): The type string of the instrument requested.
            Must be in the list specified in `get_wanted_instrument.()`.

    Raises:
        ValueError: If the instrument with the given type cannot be found in the dict of the initialized
            instruments.
        RuntimeError: If the instrument with the given type is not initialized yet.

    Returns:
        Instrument: Initialised instrument driver.
    """
    for (itype, _), instr in self.instruments.items():
        if itype == instrument_type:
            if instr is not None:
                return instr
            else:
                raise RuntimeError("Instrument with type " + str(instrument_type) + " not initialized.")
    else:
        raise ValueError("No instrument with type " + str(instrument_type) + " in dict of initialized instruments.")

get_name_with_id()

Returns the measurements name property and the unique id for this measurement's instance.

Source code in LabExT/Measurements/MeasAPI/Measurement.py

def get_name_with_id(self) -> str:
    """Returns the measurements `name` property and the unique id for this measurement's instance.
    """
    return str(self.name) + " (shortened id = " + self.id.hex[-5:] + ")"

get_non_sweepable_parameters() staticmethod

A dict mapping names of the parameters that are explicitly non-sweepable to the corresponding MeasParam.

If all parameters are sweepable this method should return an empty dict. The default implementation also returns an empty dict.

Returns:

Type	Description
Dict[str, MeasParam]	dict[str, MeasParam]: names of the parameters that aren't sweepable mapped to the corresponding parameters

Source code in LabExT/Measurements/MeasAPI/Measurement.py

@staticmethod
def get_non_sweepable_parameters() -> Dict[str, MeasParam]:
    """A `dict` mapping names of the parameters that are explicitly non-sweepable to the corresponding `MeasParam`.

    If all parameters are sweepable this method should return an empty `dict`.
    The default implementation also returns an empty `dict`.

    Returns:
        dict[str, MeasParam]: names of the parameters that aren't sweepable mapped to the corresponding parameters
    """
    return dict()

get_wanted_instrument() staticmethod

The list of all instrument types (strings) required in this measurement.

Inside the algorithm, you can access the instantiated instrument driver classes by accessing the instruments argument which is a dict. The list you return in this method will be the keys of said dict.

If you want to use more than one instrument of the same type, you can add a number after the instrument type. So to include two lasers and one power meter, I would return: ['Laser 1', 'Laser 2', 'PowerMeter'].

This method must be overriden for any working measurement implementation. See the New Measurement Algorithm page.

Returns:

Name	Type	Description
list	List[str]	the elements are strings of instrument types as available in instruments.config

Source code in LabExT/Measurements/MeasAPI/Measurement.py

@staticmethod
def get_wanted_instrument() -> List[str]:
    """The list of all instrument types (strings) required in this measurement.

    Inside the `algorithm`, you can access the instantiated instrument driver classes by accessing the
    `instruments` argument which is a dict. The list you return in this method will be the keys of said dict.

    If you want to use more than one instrument of the same type, you can add a number after the instrument type.
    So to include two lasers and one power meter, I would return: `['Laser 1', 'Laser 2', 'PowerMeter']`.

    This method must be overriden for any working measurement implementation. See
    [the New Measurement Algorithm page](./code_new_meas_example.md).

    Returns:
        list: the elements are strings of instrument types as available in instruments.config
    """
    raise NotImplementedError()

init_instruments()

Instantiates instrument drivers according to self.selected_instruments and saves them in self.instruments

This method gets called from the LabExT GUI and does not need to be invoked by the user.

Raises:

Type	Description
RuntimeError	In case any instrument could not be initilized. Sometimes initialization fails silently...

Source code in LabExT/Measurements/MeasAPI/Measurement.py

def init_instruments(self):
    """Instantiates instrument drivers according to `self.selected_instruments` and saves them in `self.instruments`

    This method gets called from the LabExT GUI and does not need to be invoked by the user.

    Raises:
        RuntimeError: In case any instrument could not be initilized. Sometimes initialization fails silently...
    """
    for instr_class in self.get_wanted_instrument():
        self._experiment_manager.instrument_api.create_instrument_obj(instr_class,
                                                                      self.selected_instruments,
                                                                      self.instruments)
    # check that all instruments were correctly initialized, if this is not the case, we raise an Exception
    if not all(inst is not None for inst in self.instruments.values()):
        raise RuntimeError('Instruments were not initialized correctly.')

measure(device, data, **kwargs)

Gathers the parameters and instruments set via GUI and executes self.algorithm() with correct arguments.

First checks whether all the needed contents are present, and if so starts execution of the algorithm. This function can take some optional arguments, namely parameters and instruments, to override the already saved ones.

Furthermore, there are modes in place to fill missing parameters automatically. The flags check_instr and check_param can take various (static) values, that will dictate how measurement will handle missing parameters and instruments.

There should be no need for a sub-class to overwrite this method.

Parameters:

Name	Type	Description	Default
device	Device	Device instance on which the measurement is performed. Allows to adapt measurement algorithm according to some device property.	required
data	dict	Dictionary in which we store the result of the measurement.	required
**kwargs		'instruments' An optional dict of instrument drivers. 'parameters' An optional dict of some parameters. Can be filled partially!	{}

Raises:

Type	Description
ValueError	If some instrument or parameter is missing and the check_ flags are set to 'Raise'.

Source code in LabExT/Measurements/MeasAPI/Measurement.py

def measure(self, device, data, **kwargs):
    """Gathers the parameters and instruments set via GUI and executes `self.algorithm()` with correct arguments.

    First checks whether all the needed contents are present, and if so starts execution of the algorithm. This
    function can take some optional arguments, namely parameters and instruments, to override the already saved
    ones.

    Furthermore, there are modes in place to fill missing parameters automatically. The flags check_instr and
    check_param can take various (static) values, that will dictate how measurement will handle missing parameters
    and instruments.

    There should be no need for a sub-class to overwrite this method.

    Arguments:
        device (Device): Device instance on which the measurement is performed. Allows to adapt measurement
            algorithm according to some device property.
        data (dict): Dictionary in which we store the result of the measurement.
        **kwargs: `'instruments'` An optional dict of instrument drivers. `'parameters'` An optional dict of
            some parameters. Can be filled partially!

    Raises:
        ValueError: If some instrument or parameter is missing and the check_ flags are set to `'Raise'`.
    """
    # update the attributes of measurement class, if allowed
    allowed_keys = {"parameters", "instruments"}
    self.__dict__.update((k, v) for k, v in kwargs.items() if k in allowed_keys)

    # check instruments
    for i in self.get_wanted_instrument():
        for (itype, _), instr in self.instruments.items():
            if itype == i:
                if instr is not None:
                    break
                else:
                    if type(self).check_instr == 'Debug':
                        self.logger.warning("Instrument " + i + " not initialized.")
                    elif type(self).check_param == 'Raise':
                        raise ValueError("Instrument not initialized: " + i)
        else:
            if type(self).check_instr == 'Debug':
                self.logger.warning("Instrument " + i + " not found.")
            elif type(self).check_param == 'Raise':
                raise ValueError("Instrument not found: " + i)

    # remove class name from key, s.t. the algorithm method has direct access via the names:
    instr_dict_no_classnames = {k: v for (k, _), v in self.instruments.items()}

    # check parameters
    for k, v in self.get_default_parameter().items():
        if k not in self._parameters:
            if type(self).check_param == 'Debug':
                self.logger.warning("Did not find parameter " + k)
            elif type(self).check_param == 'Auto':
                self._parameters[k] = v
            elif type(self).check_param == 'Raise':
                raise ValueError("Parameter not found: " + k)

    return self.algorithm(device, data, instr_dict_no_classnames, self.parameters)

open_side_windows()

Include any code you want to be executed on the "open side windows" button for the measurement.

Source code in LabExT/Measurements/MeasAPI/Measurement.py

def open_side_windows(self):
    """Include any code you want to be executed on the "open side windows" button for the measurement.
    """
    self.logger.warning('There are no side windows defined but open_side_windows() was called.')

setup_return_dict() classmethod

Gives the absolute bare minimum of keys which need to be filled in data dictionary in an algorithm() run.

Returns:

Name	Type	Description
dict	Dict[str, Dict]	The minimum set of keys for a data dictionary necessary to populate during a call of algorithm().

Source code in LabExT/Measurements/MeasAPI/Measurement.py

@classmethod
def setup_return_dict(cls) -> Dict[str, Dict]:
    """Gives the absolute bare minimum of keys which need to be filled in `data` dictionary in an `algorithm()` run.

    Returns:
        dict: The minimum set of keys for a `data` dictionary necessary to populate during a call of `algorithm()`.
    """
    data = {'measurement settings': {}, 'values': {}}
    return data

store_new_param(new_params)

Used as callback function for the GUI to set parameters of the measurement.

Source code in LabExT/Measurements/MeasAPI/Measurement.py

def store_new_param(self, new_params):
    """Used as callback function for the GUI to set parameters of the measurement.
    """
    self.parameters = new_params

LabExT Copyright (C) 2021 ETH Zurich and Polariton Technologies AG This program is free software and comes with ABSOLUTELY NO WARRANTY; for details see LICENSE file.

MeasParam

Implementation of a single measurement parameter.

Should never be used directly, only the subclasses in this file should be used.

Attributes:

Name	Type	Description
value	Union[str, float, int, bool, list]	The value which the parameter represents
unit	str	What unit the parameter has. Purely visual as a help for the user, does not influence calculations.
extra_type		Extra type, should be removed in future versions.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

class MeasParam:
    """Implementation of a single measurement parameter.

    Should never be used directly, only the subclasses in this file should be used.

    Attributes:
        value: The value which the parameter represents
        unit (str): What unit the parameter has. Purely visual as a help for the user, does not influence calculations.
        extra_type: Extra type, should be removed in future versions.
    """

    def __init__(self, value: Optional[Union[str, float, int, bool, list]] = None, unit=None, extra_type=None):
        """Constructor.

        Arguments:
            value: The value which the parameter represents
            unit (str): What unit the parameter has. Purely visual as a help for the user, does not influence calculations.
            extra_type: Extra type, should be removed in future versions.
        """
        self.value: Union[str, float, int, bool, list] = value
        self.unit = unit
        # TODO: consider removing this
        self.extra_type = extra_type

    def copy(self) -> "MeasParam":
        """Creates and returns a shallow copy of this `MeasParam`.
        """
        new = type(self)(self.value, self.unit, self.extra_type)
        return new

    def as_dict(self):
        """Returns the stored value as part of a dict.
        """
        d = {'value': self.value}
        if self.unit is not None:
            d.update({'unit': self.unit})
        return d

    @property
    def sweep_type(self) -> Union[None, Literal["binary", "range"]]:
        """Returns the type of sweep this parameter supports.
        """
        return None

    def __str__(self):
        """Converts this parameter to a string.
        """
        return str(type(self)) + ": " + str(self.value) + " " + str(self.unit)

sweep_type: Union[None, Literal['binary', 'range']] property

Returns the type of sweep this parameter supports.

__init__(value=None, unit=None, extra_type=None)

Constructor.

Parameters:

Name	Type	Description	Default
value	Optional[Union[str, float, int, bool, list]]	The value which the parameter represents	None
unit	str	What unit the parameter has. Purely visual as a help for the user, does not influence calculations.	None
extra_type		Extra type, should be removed in future versions.	None

Source code in LabExT/Measurements/MeasAPI/Measparam.py

def __init__(self, value: Optional[Union[str, float, int, bool, list]] = None, unit=None, extra_type=None):
    """Constructor.

    Arguments:
        value: The value which the parameter represents
        unit (str): What unit the parameter has. Purely visual as a help for the user, does not influence calculations.
        extra_type: Extra type, should be removed in future versions.
    """
    self.value: Union[str, float, int, bool, list] = value
    self.unit = unit
    # TODO: consider removing this
    self.extra_type = extra_type

__str__()

Converts this parameter to a string.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

def __str__(self):
    """Converts this parameter to a string.
    """
    return str(type(self)) + ": " + str(self.value) + " " + str(self.unit)

as_dict()

Returns the stored value as part of a dict.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

def as_dict(self):
    """Returns the stored value as part of a dict.
    """
    d = {'value': self.value}
    if self.unit is not None:
        d.update({'unit': self.unit})
    return d

copy()

Creates and returns a shallow copy of this MeasParam.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

def copy(self) -> "MeasParam":
    """Creates and returns a shallow copy of this `MeasParam`.
    """
    new = type(self)(self.value, self.unit, self.extra_type)
    return new

MeasParamBool

Bases: MeasParam

Implements a MeasParam that represents a boolean.

Gets rendered as a check-box.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

class MeasParamBool(MeasParam):
    """Implements a MeasParam that represents a boolean.

    Gets rendered as a check-box.
    """

    @property
    def sweep_type(self) -> Union[Literal['binary', 'range'], None]:
        return "binary"

    def __init__(self, value=None, unit=None, extra_type=None):
        super().__init__(value, unit, extra_type)

MeasParamFloat

Bases: MeasParam

Implements a MeasParam that represents a floating-point number.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

class MeasParamFloat(MeasParam):
    """Implements a MeasParam that represents a floating-point number.
    """

    def __init__(self, value=None, unit=None, extra_type=None):
        super().__init__(value, unit, extra_type)

    @property
    def value(self):
        return self._value

    @property
    def sweep_type(self) -> Union[Literal['binary', 'range'], None]:
        return "range"

    @value.setter
    def value(self, new_val):
        if type(new_val) is float:
            self._value = new_val
        else:
            raise ValueError(
                "MeasParamFloat needs a float assigned to value. Tried to assign: " + str(new_val) + " of type "
                + str(type(new_val)))

MeasParamInt

Bases: MeasParam

Implements a MeasParam that represents an integer number.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

class MeasParamInt(MeasParam):
    """Implements a MeasParam that represents an integer number.
    """

    def __init__(self, value=None, unit=None, extra_type=None):
        super().__init__(value, unit, extra_type)
        self.value = value

    @property
    def value(self):
        return self._value

    @property
    def sweep_type(self) -> Union[Literal['binary', 'range'], None]:
        return "range"

    @value.setter
    def value(self, new_val):
        if type(new_val) is int:
            self._value = new_val
        else:
            raise ValueError(
                "MeasParamInt needs an integer assigned to value. Tried to assign: " + str(new_val) + " of type "
                + str(type(new_val)))

MeasParamList

Bases: MeasParam

Implements a MeasParam that represents a selection as part of a list.

Aside from the MeasParam arguments, needs the options argument, a list of all possible selections. Gets rendered as a drop-down menu in LabExT GUI.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

class MeasParamList(MeasParam):
    """Implements a MeasParam that represents a selection as part of a list.

    Aside from the MeasParam arguments, needs the `options` argument, a list of all possible selections. Gets rendered
    as a drop-down menu in LabExT GUI.
    """

    def __init__(self, options, value=None, unit=None, extra_type=None):
        """Constructor.

        Arguments:
            options (list): all the options this MeasParam can take
        """
        super().__init__(value, unit, extra_type)
        self.options = options

    def copy(self) -> MeasParam:
        return MeasParamList(self.options, self.value, self.unit, self.extra_type)

    def __str__(self):
        return str(type(self)) + ": " + str(self.options) + " selected: " + str(self.value)

__init__(options, value=None, unit=None, extra_type=None)

Constructor.

Parameters:

Name	Type	Description	Default
options	list	all the options this MeasParam can take	required

Source code in LabExT/Measurements/MeasAPI/Measparam.py

def __init__(self, options, value=None, unit=None, extra_type=None):
    """Constructor.

    Arguments:
        options (list): all the options this MeasParam can take
    """
    super().__init__(value, unit, extra_type)
    self.options = options

MeasParamString

Bases: MeasParam

Implements a MeasParam that represents a string.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

class MeasParamString(MeasParam):
    """Implements a MeasParam that represents a string.
    """

    def __init__(self, value=None, unit=None, extra_type=None):
        super().__init__(value, unit, extra_type)

MeasParamAuto(value=None, unit=None, extra_type=None, selected=None)

Automatically chooses the correct type of MeasParam based on the type of the value argument.

Source code in LabExT/Measurements/MeasAPI/Measparam.py

def MeasParamAuto(value=None, unit=None, extra_type=None, selected=None):
    """Automatically chooses the correct type of MeasParam based on the type of the `value` argument.
    """
    if type(value) is str:
        return MeasParamString(value=value, unit=unit, extra_type=extra_type)
    elif type(value) is bool:
        return MeasParamBool(value=value, unit=unit, extra_type=extra_type)
    elif type(value) is list:
        return MeasParamList(options=value, value=selected, unit=unit, extra_type=extra_type)
    elif type(value) is int:
        return MeasParamInt(value=value, unit=unit, extra_type=extra_type)
    else:
        return MeasParamFloat(value=value, unit=unit, extra_type=extra_type)