matplotlib-users

[Matplotlib-users] Bug in colorbar labeling

[Curtis C. <cu...@hi...>]

Hi,

I have been using the colorbar() method along with pcolor to make image
plots of data.  Normally, the colorbar legend is correct.  However, when
the range of numbers to plot is less than 1, such as 10^-3 - 2*10^-3, the
colorbar labels just show up as 0.0 on the top and bottom.

Thanks,
Curtis

[Matplotlib-users] Re: Bug in colorbar labeling

[Curtis C. <cu...@hi...>]

Hi all,

I have a fix for the problem mentioned.  In the latest release, subdir
matploblib-0.60.2/matplotlib/matlab.py line 542 there is a bug.  It should
read:

cax.set_yticklabels([tickfmt%tick for tick in cticks])

instead of

cax.set_yticklabels(['%1.1f'%tick for tick in cticks])

so as to take advantage of the optional input parameter tickfmt (format
specifier) for the colorbar labels.  With this change, the colorbar labels
come out fine and adjust properly according to the input format specifier.

Thanks,
Curtis

[Matplotlib-users] Re: Bug in colorbar labeling

[Curtis C. <cu...@hi...>]

I reported this bug July 19 for an earlier version of Matplotlib, but it
is still relevent through Matplotlib v. 0.62-4:

> I have been using the colorbar() method along with pcolor to make image
> plots of data.  Normally, the colorbar legend is correct.  However, when
> the range of numbers to plot is less than 1, such as 10^-3 - 2*10^-3, the
> colorbar labels just show up as 0.0 on the top and bottom.

The key will be to get the tickfmt option into the colorbar() function
working properly.

Cheers,
Curtis

Re: [Matplotlib-users] Re: Bug in colorbar labeling

[John H. <jdh...@ac...>]

>>>>> "Curtis" == Curtis Cooper <cu...@hi...> writes:

    Curtis> I reported this bug July 19 for an earlier version of
    Curtis> Matplotlib, but it is still relevent through Matplotlib
    Curtis> v. 0.62-4:

Could you test this with 0.63 and if the problem persists post a
minimal script that exposes the bug?

Thanks,
JDH

Re: [Matplotlib-users] Re: Bug in colorbar labeling

[Curtis C. <cu...@hi...>]

> Could you test this with 0.63 and if the problem persists post a
> minimal script that exposes the bug?

In matplotlib-0.63.0, I can't even get the examples pcolor_demo.py and
pcolor_demo2.py to work properly.  My code mimics these examples closely.
Once they are working again, I will send you an example of the colorbar
tick format issue.

Cheers,
Curtis

Re: [Matplotlib-users] Re: Bug in colorbar labeling

[John H. <jdh...@ac...>]

>>>>> "Curtis" == Curtis Cooper <cu...@hi...> writes:

    >> Could you test this with 0.63 and if the problem persists post
    >> a minimal script that exposes the bug?

    Curtis> In matplotlib-0.63.0, I can't even get the examples
    Curtis> pcolor_demo.py and pcolor_demo2.py to work properly.  My
    Curtis> code mimics these examples closely.  Once they are working
    Curtis> again, I will send you an example of the colorbar tick
    Curtis> format issue.

Strange.  pcolor_demo.py and pcolor_demo2.py work fine for me on linux
and win32.

Try rm -rf site-packages/matplotlib and the 'build' dir of your
matplotlib install tree, and reinstall.

What, by the way, does it mean to "not work properly".  Is this a
crash?  Note an image interpolation bug was fixed in 0.63.0 which will
cause the axes limits to be a little different for imshow calls than
they were before.  Earlier versions of matplotlib set the viewlim to
hide the edge artifacts, which no longer exist.

JDH

Re: [Matplotlib-users] Re: Bug in colorbar labeling

[Curtis C. <cu...@hi...>]

> Try rm -rf site-packages/matplotlib and the 'build' dir of your
> matplotlib install tree, and reinstall.

This worked.  I didn't realize I had to delete the
site-packages/matplotlib before installing over an old version.

Re: [Matplotlib-users] Re: Bug in colorbar labeling

[John H. <jdh...@ac...>]

>>>>> "Curtis" == Curtis Cooper <cu...@hi...> writes:

    Curtis> This worked.  I didn't realize I had to delete the
    Curtis> site-packages/matplotlib before installing over an old
    Curtis> version.

You don't normally, but this is usually my first line of defense when
something fails in one place that isn't failing in another.

So does the colorbar bug persist?

JDH

Re: [Matplotlib-users] Re: Bug in colorbar labeling

[Curtis C. <cu...@hi...>]

> So does the colorbar bug persist?
>

It appears to have been fixed!  The colorbar labeling automatically
determines the appropriate number of digits (or if scientific notation is
necessary) for the text labels on the colorbar.  You might want to
activate the tickfmt optional parameter that is still present in the
source code, as this gives the user direct control over the number of
digits displayed, but at least the labels can be distinguished in the
current version of the library.

Thanks!
Curtis