Labels

class pypulseqpp.sequences.Labels

Bases: LabelWriter

Writer of label events for the sticky label state of a Pulseq sequence.

A label keeps its value across blocks until an event changes it, so a block carries the events of the labels it changes and no others. Calling an instance with each label’s new value, by its Pulseq name, returns the events to add to the block, empty when nothing changed. An unchanged value writes nothing, a change equal to the label’s previous change is an INC, which a scan repeats as one event, and any other change is a SET. A change of ONCE calls restart() first, so every label passed with it is written again as a SET. An instance returns the same event object for equal statements, so the events are added to blocks as they are, not modified.

Examples

An unchanged value writes nothing, and a change equal to the label’s previous change is an INC:

>>> from pypulseqpp import sequences
>>> labels = sequences.Labels()
>>> [[(e.type, e.value) for e in labels(LIN=line)] for line in (0, 2, 4, 4, 3)]
[[('labelset', 0)], [('labelset', 2)], [('labelinc', 2)], [], [('labelset', 3)]]

Labels passed together are written in the order given:

>>> labels = sequences.Labels()
>>> [(e.label, e.type, e.value) for e in labels(LIN=0, SLC=1)]
[('LIN', 'labelset', 0), ('SLC', 'labelset', 1)]
>>> [(e.label, e.type, e.value) for e in labels(LIN=0, SLC=2, ONCE=1)]
[('LIN', 'labelset', 0), ('SLC', 'labelset', 2), ('ONCE', 'labelset', 1)]

Methods

restart

Write every label's next value as a SET, regardless of what was written before.

Examples using Labels

A sequence function

A sequence function