plt.plot(..., c="...") doesn't always set the color properly

[anntzer]

Specifically it is dependent on PYTHONHASHSEED:

$  PYTHONHASHSEED=1 python -c 'from pylab import *; plot([1, 2], [3, 4], c="g"); show()' # ==> ok
$ PYTHONHASHSEED=2 python -c 'from pylab import *; plot([1, 2], [3, 4], c="g"); show()' # ==> blue line

Pretty sure the issue happens in _process_plot_var_args._makeline which just checks whether the color kwargs is given (but doesn't check for c); if it is not it fetches the next color and uses it as the color kwarg, and whether color or c wins depends on the current hashing seed.

A bit scary...

version: matplotlib 1.4.3 packaged by Arch Linux

[efiring]

This is fixed in master.

On 8/4/15, Antony Lee notifications@github.com wrote:

Specifically it is dependent on PYTHONHASHSEED:

$  PYTHONHASHSEED=1 python -c 'from pylab import *; plot([1, 2], [3, 4],
c="g"); show()' # ==> ok
$ PYTHONHASHSEED=2 python -c 'from pylab import *; plot([1, 2], [3, 4],
c="g"); show()' # ==> blue line

Pretty sure the issue happens in _process_plot_var_args._makeline which
just checks whether the color kwargs is given (but doesn't check for c);
if it is not it fetches the next color and uses it as the color kwarg, and
whether color or c wins depends on the current hashing seed.

A bit scary...

version: matplotlib 1.4.3 packaged by Arch Linux

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#4866

[tacaswell]

And the workaround is to simple use 'color' instead of 'c'