How do I write a stim diagram to a file?

Question

I made an svg diagram from a stim circuit:

import stim
circuit = stim.Circuit("""
    H 0
    CX 0 1
    M 0 1
""")
diagram = circuit.diagram("timeline-svg")
display(diagram)

I tried to write the diagram to a file, but I got an error:

with open('diagram.svg', 'w') as f:
    f.write(diagram)

TypeError: write() argument must be str, not stim._DiagramHelper

How do I save the diagram to an SVG image file?

Got asked this outside of QCSE. Copying it here for posterity. — Craig Gidney, Dec 01 '23 at 06:36

score 2 · Answer 1 · answered Dec 01 '23 at 06:36

Do this:

with open('diagram.svg', 'w') as f:
    print(diagram, file=f)

Or this:

with open('diagram.svg', 'w') as f:
    f.write(str(diagram))

The stim._DiagramHelper class has a __str__ method that returns the contents of the SVG file. The diagram method could just return a string... but then tools like Jupyter notebook wouldn't display it as an image.

How do I write a stim diagram to a file?

1 Answers1