Sequence.repetition

Sequence.repetition()

Return the repeating unit of the block table.

Returns:

• size (int) – Blocks per repetition; the whole sequence when it does not repeat, and zero when it has no blocks.

• start (int) – 1-based block at which the first repetition starts, always 1.

Notes

The repetition is the shortest period of the block-definition stream from the first block that every later block repeats, the last copy possibly cut short; failing that, the shortest period dividing the table over which blocks match in duration and in the channels they play; failing both, the whole sequence. A slice acquired with its own preparation and dummy shots is therefore one repetition, and a block played once makes the whole sequence one. A TRsize definition shorter than the sequence, dividing it and repeated by the blocks, is taken instead, so a longer hyper-TR can be declared. Nothing is written into the sequence.

Examples

>>> import numpy as np
>>> import pypulseqpp as pp
>>> seq = pp.Sequence(pp.Opts())
>>> pulse = pp.make_block_pulse(np.pi / 2, duration=1e-3)
>>> for _ in range(4):
...     _ = seq.add_block(pulse)
...     _ = seq.add_block(pp.make_delay(10e-3))
>>> seq.repetition()
(2, 1)
>>> seq.get_definition("TRsize")
''