simple example not working

[alexdennis312]

the simple example under docs didn't work for me when trying to run. It gives me the error "ValueError: setting an array element with a sequence. The requested array has an inhomogeneous shape after 1 dimensions. The detected shape was (1024,) + inhomogeneous part."

Here is my code:

from cheetah import (
    BPM,
    Drift,
    HorizontalCorrector,
    ParameterBeam,
    Segment,
    VerticalCorrector,
    ParticleBeam,
    Element
)

import torch
import math
import numpy as np

segment = Segment(
    elements=[
        BPM(name="BPM1SMATCH"),
        Drift(length=torch.tensor([1.0])),
        BPM(name="BPM6SMATCH"),
        Drift(length=torch.tensor([1.0])),
        VerticalCorrector(length=torch.tensor([0.3]), name="V7SMATCH"),
        Drift(length=torch.tensor([0.2])),
        HorizontalCorrector(length=torch.tensor([0.3]), name="H10SMATCH"),
        Drift(length=torch.tensor([7.0])),
        HorizontalCorrector(length=torch.tensor([0.3]), name="H12SMATCH"),
        Drift(length=torch.tensor([0.05])),
        BPM(name="BPM13SMATCH"),
    ]
)

segment.V7SMATCH.angle = torch.tensor([3.142e-3])
incoming_beam = ParticleBeam.from_astra("../../ACHIP_EA1_2021.1351.001")

outgoing_beam = segment.track(incoming_beam)

segment.plot_overview(beam=incoming_beam)

Everything seems to work except for the segment.plot_overview(beam=incoming_beam) line, which is also where the error appears.

[jank324]

Which version of Cheetah are you running?

[alexdennis312]

Which version of Cheetah are you running?

I'm using version 0.6.3

[jank324]

Which version of Cheetah are you running?

I'm using version 0.6.3

Then your issue is that the code example you are using is from the current master branch, which is a pre-release version of 0.7.0. There is a breaking change going from 0.6.* to 0.7, which changes how you pass parameters to Cheetah Elements (see the CHANGELOG.md file and #116).

If you use the code example from the v0.6.3 tag, everything should work. Alternatively you could also directly install 0.7 from master with

pip install git+https://github.com/desy-ml/cheetah.git

and use the code example you have been using.

Let me know if this works for you.

[alexdennis312]

Which version of Cheetah are you running?

I'm using version 0.6.3

Then your issue is that the code example you are using is from the current master branch, which is a pre-release version of 0.7.0. There is a breaking change going from 0.6.* to 0.7, which changes how you pass parameters to Cheetah Elements (see the CHANGELOG.md file and #116).

If you use the code example from the v0.6.3 tag, everything should work. Alternatively you could also directly install 0.7 from master with

pip install git+https://github.com/desy-ml/cheetah.git

and use the code example you have been using.

Let me know if this works for you.

This worked! Thank you so much for your help!