pcdsdevices.signal.AvgSignal

class pcdsdevices.signal.AvgSignal(signal: Signal | str, averages: int, duration: float | None = None, *, name: str, parent: Device | None = None, **kwargs)

Signal that acts as a rolling average of another signal.

Optionally, the rolling average can be reset every time the trigger method is called (e.g. at every point in a bluesky scan). This is the behavior if you specific a duration for the trigger using the duration argument.

This will subscribe to a signal, and fill an internal buffer with values from SUB_VALUE. It will update its own value to be the mean of the last n accumulated values, up to the buffer size. If we haven’t filled this buffer, this will still report a mean value composed of all the values we’ve receieved so far.

Warning: this means that if we only have recieved ONE value, the mean will just be the mean of a single value!

Parameters:

signal (Signal or str) – Any subclass of ophyd.signal.Signal that returns a numeric value. This signal will be subscribed to be AvgSignal to calculate the mean. Parent classes can pass a str instead that matches the attr name of one of their component signals.
averages (int) – The number of SUB_VALUE updates to include in the average. New values after this number is reached will begin overriding old values.
duration (float, optional) – The number of seconds to wait before returning trigger complete. Nominally this should be set to averages divided by the expected update rate of the signal. If omitted, we will not reset the buffer or wait for values at scan points.

Methods

describe()

Provide schema and meta-data for read()

This keys in the OrderedDict this method returns must match the keys in the OrderedDict return by read().

This provides schema related information, (ex shape, dtype), the source (ex PV name), and if available, units, limits, precision etc.

Returns:: data_keys (OrderedDict) – The keys must be strings and the values must be dict-like with the event_model.event_descriptor.data_key schema.

get(**kwargs): The readback value

read()

Put the status of the signal into a simple dictionary format for data acquisition

Returns:: dict

read_configuration(): Dictionary mapping names to value dicts with keys: value, timestamp

reset_buffer() → None: Re-initialize the avg signal buffer.

set(value, *, timeout=None, settle_time=None, **kwargs)

Set the value of the Signal and return a Status object.

Returns:: st (Status) – This status object will be finished upon return in the case of basic soft Signals

trigger() → Status: Call that is used by bluesky prior to read()

Attributes

SUB_META = 'meta'

averages: The size of the internal buffer of values to average over.

connected

high_limit: The high, inclusive control limit for the Signal

hints: Field hints for plotting

kind

limits: The control limits (low, high), such that low <= value <= high

low_limit: The low, inclusive control limit for the Signal

metadata: A copy of the metadata dictionary associated with the signal

metadata_keys: Metadata keys that will be passed along on value subscriptions

read_access: Can the signal be read?

source_name

subscriptions: ClassVar[FrozenSet[str]] = frozenset({'meta', 'value'})

timestamp: Timestamp of the readback value

tolerance: The absolute tolerance associated with the value.

value: The signal’s value

write_access: Can the signal be written to?