Hi Sam,

That's because this error is caused by yt doing something incorrect when interfacing with NumPy internally. Whenever yt raises a mysterious exception like this from something its doing internally it's almost certainly due to a bug in yt or yt failing to convert the internal error into a more understandable user-facing error.

First, try updating yt, the newest version is 3.5.1 and it's possible that your issue has already been fixed.

If that doesn't work, can you make a full runnable example that triggers this issue? If you can, use one of the public test datasets on yt-project.org/data but if its somehow related to properties of the data you are working with, you can share a dataset using the "yt upload" subcommand:

$ yt upload some_file.tar.gz

That will print out a URL you can share once its done uploading.

Once you have that you should open a bug report on yt's github including the full example that triggers the issue:




On Wed, Jun 12, 2019 at 9:55 AM Sam Patrick via yt-users <yt-users@python.org> wrote:
Hi all,

I'm trying to write a simple piece of code which produces a phase plot
of the entire dataset. I'm currently using yt version 3.5.0 and Python
version 3.7.1. Essentially what I have is:

val, loc = ds.find_max('density')
ad = ds.all_data()
plot = yt.PhasePlot(ad, "density", "temperature", "cell_mass",
plot.set_unit('cell_mass', 'Msun')
filename = "phase_plot_z={:.2f}.png".format(ds.current_redshift)

However when I try running the code I get the following error:

Traceback (most recent call last):
   File "phase_plot.py", line 14, in <module>
     plot = yt.PhasePlot(ad, "density", "temperature", "cell_mass",
line 931, in __init__
line 1207, in create_profile
     obj.add_fields([field for field in fields])
line 129, in add_fields
     self._bin_chunk(chunk, fields, temp_storage)
line 627, in _bin_chunk
     bin_ind_y = np.digitize(bf_y, self.y_bins) - 1
ValueError: bins must be monotonically increasing or decreasing

I'm not entirely sure what's happening since there's no part of the code
which is interfacing with binning directly. Any light shed on this issue
would be much appreciated.

Many thanks,
Sam Patrick
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