Sequence

class pypulseqpp.Sequence

A Pulseq sequence containing events, blocks and definitions.

Parameters:

• system (Opts, default=None) – System limits and rasters. Defaults to the shared system; rasters are recorded in the native sequence.

• use_block_cache (bool, default=True) – Compatibility flag, retained but not used to cache decoded blocks.

Attributes:

• system (Opts | None, default=None) – The limits the sequence was constructed with.

• num_blocks (int) – Number of blocks; equivalent to len(seq).

• block_durations (MutableMapping[int, float]) – Duration of each block in seconds, keyed by 1-based block index. Assigning an entry changes the stored block duration.

• block_events (dict[int, NDArray[np.int32]]) – Event IDs of each block, keyed by 1-based block index: delay, RF, gx, gy, gz, ADC and extension. The delay column is zero for Pulseq 1.5. Reading it allocates a dictionary for all blocks.

• definitions (dict[str, Any]) – The definitions written to the [DEFINITIONS] section.

• grad_raster_time (float) – Gradient raster in seconds.

• rf_raster_time (float) – RF raster in seconds.

• adc_raster_time (float) – ADC dwell raster in seconds.

• block_duration_raster (float) – Block duration raster in seconds; every block duration is a whole number of these.

• version_major (int) – Major version of the Pulseq format the sequence is held as. A file older than 1.5 is converted as it is read, so this is the format of the sequence in memory, not the version its file declared.

• version_minor (int) – Minor version of the format the sequence is held as.

• version_revision (int) – Revision of the format the sequence is held as.

• signature_type (str | None) – Hash algorithm of the signature carried by the last file written, or by the last binary file read: 'md5', or None when it had none.

• signature_file (str | None) – Format that file was written in, 'text' or 'bin'.

• signature_value (str | None) – The signature itself.

Examples

>>> import pypulseqpp as pp
>>> seq = pp.Sequence(pp.Opts())
>>> seq.add_block(pp.make_trapezoid("x", area=1000, duration=2e-3))
1
>>> seq.add_block(pp.make_delay(1e-3))
2
>>> seq.num_blocks, round(seq.duration()[0], 6)
(2, 0.003)

Blocks

add_block	Append one block playing events.
set_block	Write events over the block at index, 1-based.
get_block	Decode a block by its 1-based index.
find_block_by_time	Return the 1-based index of the block containing time t in seconds.
remove_duplicates	Merge identical library rows and renumber the references to them.

Definitions and labels

set_definition	Record key in [DEFINITIONS].
get_definition	Return the value recorded for key, or '' when it is not defined.
copy_definitions	Copy every definition from other_seq into this sequence.
evaluate_labels	Evaluate running label values in block order.
add_trid	Append a block setting TRID to the number assigned to label_name.
get_or_create_trid_id	Return the TRID number assigned to label_name, assigning one if new.

Soft delays

apply_soft_delay	Set each named soft delay to the value given.
get_default_soft_delay_values	Return each soft delay's default value.

Reading and writing

read	Replace this sequence with the one in file_path.
write	Write Pulseq text and record its signature metadata.
write_binary	Write Pulseq binary, with float32 shape samples.
write_v141	Write Pulseq 1.4.1 text, for an interpreter predating Pulseq 1.5.
libraries	Return the block table and every library, as a Pulseq file of the sequence holds them.

Waveforms and k-space

waveforms	Return gradient corners as time (s) over amplitude (Hz/m), per axis.
waveforms_and_times	Return the gradient waveforms, the RF pulse timing and the ADC sampling.
get_gradients	Return physical-axis gradient splines in Hz/m over seconds.
calculate_kspace	Integrate physical-axis gradients with excitation resets and refocusing.
adc_kspace	Return the k-space location of each ADC sample, in 1/m.
adc_times	Return ADC sample times (s) and per-window frequency (Hz) and phase (rad).
rf_times	Return RF pulse centre times with their frequency and phase offsets.
duration	Return total duration, block count and per-event block counts.

Checks and reports

check_timing	Check timing, gradient continuity and the stored total duration.
test_report	Return sequence timing, encoding and gradient statistics, formatted as text.
test_report_dict	Return timing, encoding and gradient statistics.
calc_rf_power	Return the RF's mean power, peak power, RMS amplitude and energy.
rf_flip_angles	Return the flip angle of each RF event of the library, in degrees.
rf_channels	Return the transmit channels each RF event of the library holds.

Gradient edits

flip_grad_axis	Negate the amplitude of every gradient on axis.
mod_grad_axis	Scale the amplitude of every gradient on axis by modifier.

Plotting

plot	Open the sequence in the SeqEyes viewer.
paper_plot	Draw a publication-style diagram of one repetition, using mrsd.