system.Parameter

Define a measurement parameter.

Usage

system.Parameter(
    name,
    unit,
    setter=None,
    getter=None,
    default=None,
    dtypes=None,
    chunks=None,
    trigger=None,
    setter_args=None,
    setter_kwargs=None,
    getter_args=None,
    getter_kwargs=None,
    trigger_args=None,
    trigger_kwargs=None,
    label=None
)

This class describes one parameter in matrix. It can define a single or multiple columns of the measurement.

Parameters

name: str or list of str

Name of the column(s) as string or list of strings. If this is a list, make sure unit, default and chunks have same length.

unit: str or list of str

Unit of the column(s) as string or list of strings.

default: float or list of floats = None

Default value for parameter. If not None this value is always used unless another value is specified in the measurement. If None (default), no default value is set/used.

dtypes: str or list of str = None

Dtype specified for saving into hdf5 files, not used for ascii files. Default value is “f8” (8 byte float).

chunks: int or list of int = None

Length of the readback value. If a list is returned for a single parameter, set to the length of that list. If None (default), a chunk of 1 is assumed (readback of parameter is single float).

setter: callable, str, or list = None

Function which should be called to set the values. Must be one of:

A callable function with the call signature func(value, *args, **kwargs). For optional arguments and kwargs see setter_args/setter_kwargs.
A string with a system method/property name. If it corresponds to a method its call signature and arguments must be equal to the callable function above.
A list of the following scheme [device_name : str, method_name : str, args : tuple, kwargs : dict]. The args and kwargs entries are deprecated and should be replaced by the setter_args, setter_kwargs parameters.

getter: callable, str, or list = None

Function which should be called to fetch the values. Must be one of:

A callable function with the call signature func(*args, **kwargs). The arguments and kwargs are optional and can be supplied via getter_args/getter_kwargs.
A string with a system method/property name. If it corresponds to a method its call signature and arguments must be equal to the callable function above.
A list of the following scheme [device_name : str, method_name : str, args : tuple, kwargs : dict]. The args and kwargs entries are deprecated and should be replaced by the getter_args, getter_kwargs parameters.

trigger: callable, str, or list = None

Takes a trigger function. The options are equal to the getter options. For the optional arguments and kwargs use trigger_args/trigger_kwargs.

label: str = None

Parameters label if different from name. This might be in particular needed if an automatically generated label from a name-list is not describing the content very well.

Attributes

All parameters are set as attributes of same name.

Raises

ValueError: If parameter types or lengths are inconsistent.
TypeError: If parameter types are incorrect.