Import seq file backend

There exist two backend: pulseq_rs and pydisseqt. Which should be used when? Does it make not sense to keep just one to prevent confusion?

pulseq_rs is the new importer, compatible with 1.5 and skips the whole pydisseqt dependency.
The old one is still there for comparison, if everything works fine we can remove it

It seems like there's significant performance difference between the two parsers. Is this expected?

>>> timeit('mr0.Sequence.import_file(sequence_file, backend="pydisseqt")', setup='import MRzeroCore as mr0; from __main__ import sequence_file', number=1)
0.29288835900024424
>>> timeit('mr0.Sequence.import_file(sequence_file, backend="pulseq_rs")', setup='import MRzeroCore as mr0; from __main__ import sequence_file', number=1)
197.88033664000068

No and I never experienced such a difference. Can you share the .seq file that produced those timings?

While I cannot provide the exact sequence which I used above to get those timings, I can provide a generic sequence which gives similar-enough differences: 0.244 with pydisseqt versus 27.60 with pulseq_rs.
FYI, I had to rename the extension from .seq to .txt to attach it to this comment.

bssfp_cine.txt

The loading of the .seq file itself is fast, which hints that the problem is in the code that converts the data into the internal format for MR-zero.
Thank you for reporting this, I will revise that code as soon as possible.

Should be fixed in 4484fae / mrzerocore 1.0.5:

Sped up import by x20. Old code used linear search per repetition to find the correct pulseq plot, leading to quadratic computational cost. Now we use binary search.

This makes the new importer still x5 slower than the old one on the sequence you provided. The difference should no longer be prohibitive or explode with long sequences. Please re-open if its really bad for some sequences. (More than a couple of seconds). Will improve further in the future.

I also see quite some prolongation in import time: (mr0 1.07)

same script using 1.5 and 1.4 writing functions of pypulseq 1.5

1.4.1 - pulseq_rs : 4.84s
1.4.1 - pydisseqt : 0.27s
1.5.0 - pulseq_rs | 4.76s
1.5.0 - pydisseqt | fail (1.5 unsupported)

file is a pypulseq example mprage 2D, attached

mprage_pp.seq.txt

That's 17 times slower still..

fixed in #194 , please check and merge if ok.

Navigation Menu

Repository navigation

Import seq file backend #175

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Import seq file backend #175

Description

Activity

J-Endres commented on Jun 24, 2026

lobroc commented on Jun 25, 2026

J-Endres commented on Jul 7, 2026

lobroc commented on Jul 10, 2026

J-Endres commented on Jul 13, 2026

J-Endres commented on Jul 20, 2026

mzaiss commented on Sep 20, 2026

mzaiss commented on Sep 26, 2026

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions