plots do not scale to size

Community matplotlib-users
1

Chaitanya Krishna <icymist@...287...> writes:

When I run the script below, the xlabel and ylabel do not show up. If I
increase the figure size, it all works fine.

I am not sure if it is a bug. But, it is usual that such a thing
happens when you are making small figures (like in your case).

Arguably it is a bug, since it is reasonable to expect that when you set
an xlabel or ylabel (or, say, large yticklabels), it shows up in the
figure. There are at least two problems to solve here: what should the
user interface be like, and how can it best be implemented?

The user interface question seems difficult to me. If you set the figure
size to something small (as in this case) and then add labels, should
matplotlib reduce the area available for the plot? Or should it reduce
the font size of the labels and the tick labels, and perhaps the amount
of white space between the axes and the labels? Or some combination of
these?

The implementation question could also be somewhat hairy, since the
bounding box of text objects depends on the backend. If agg and pdf
disagree on the size of a label, is it OK to get different-looking
results in png and pdf?

--
Jouni K. Seppänen
http://www.iki.fi/jks

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This _must_ be a bug. Consider the following:
##############
import matplotlib
matplotlib.rcParams['figure.figsize'] = [8.85, 3.20]
matplotlib.use('pdf')
from pylab import *

xs = linspace(0, 2 * pi)
ys = sin(xs)
plot(xs, ys)
xlabel(r'T\_\{est\}')
ylabel('y axis')

savefig('test')
##############
Here, the vertical size is clearly large enough for a label, as it is a full inch larger than in the previous example. However, the xlabel is truncated. This _must_ be a bug. When I make a plot, I would expect that all parts of the plot appear on the plot.

As an example, in Gnuplot, the text just appears in the "right place", but is too large (overlaps the plot, etc). Hence, you see for yourself that the font size is the problem.

Anyway, it can't be the font size here, as the xlabel was completely outside the "bounding box" (I'm not sure of the terminology). To me, it just looks like a problem with the scaling - the plot looks perfectly OK in Illustrator, disregarding that it doesn't fit inside the "viewing window".

I'm not an expert, and I certainly don't know how to fix this. But I do know that other software manages this nicely. Don't get me wrong, I use matplotlib because I like it - but it should be possible to fix this problem.

Best regards,
Paul.

···

On 9. juni. 2009, at 17.18, Jouni K. Seppänen wrote:

On Tue, Jun 9, 2009 at 12:05 PM, Paul Anton Letnes <paul.anton.letnes@...120.....287... >>> > wrote:

2

This _must_ be a bug. Consider the following:
##############
import matplotlib

No it is not a bug -- mpl is doing what you tell it to do. Consider

  >>> figure()
  >>> subplot(111)
  >>> plot([1,2,3])
  >>> xlabel('hi mom', fontsize=100)

Each command has precise meaning -- the fig creates a figure using the
default size, the subplot occupies a fraction of that figure according
to the default ratios in the subplots_adjust parameters, and the
xlabel makes a label at an indicated physical size. You may not be
explicitly setting those sizes, but they are all defined via defaults
in the matplotlibrc. We try and make mpl do what you tell it to do,
not to try and out-smart you and do what we think you are telling it
to do.

Now I definitely support the idea that we should have a *feature* to
auto-adjust the subplots_adjust params and fontsizes so that it "just
works" more often. But this should be an optional feature so the user
who wants to express their intent clearly will not constantly be
stymied by mpl adjusting the sizes. Michael Droettboom has worked on
it and it is a difficult problem to get right.

JDH

···

On Wed, Jun 10, 2009 at 1:58 AM, Paul Anton Letnes<paul.anton.letnes@...287...> wrote:

3

Hm, I see. Thanks for an informative answer. I'll dig into my rcParams and matplotlibrc then...

Best regards,
Paul.

···

On 10. juni. 2009, at 14.53, John Hunter wrote:

On Wed, Jun 10, 2009 at 1:58 AM, Paul Anton > Letnes<paul.anton.letnes@...287...> wrote:

This _must_ be a bug. Consider the following:
##############
import matplotlib

No it is not a bug -- mpl is doing what you tell it to do. Consider

figure()
subplot(111)
plot([1,2,3])
xlabel('hi mom', fontsize=100)

Each command has precise meaning -- the fig creates a figure using the
default size, the subplot occupies a fraction of that figure according
to the default ratios in the subplots_adjust parameters, and the
xlabel makes a label at an indicated physical size. You may not be
explicitly setting those sizes, but they are all defined via defaults
in the matplotlibrc. We try and make mpl do what you tell it to do,
not to try and out-smart you and do what we think you are telling it
to do.

Now I definitely support the idea that we should have a *feature* to
auto-adjust the subplots_adjust params and fontsizes so that it "just
works" more often. But this should be an optional feature so the user
who wants to express their intent clearly will not constantly be
stymied by mpl adjusting the sizes. Michael Droettboom has worked on
it and it is a difficult problem to get right.

JDH

4

That is worth doing, but you needn't change the defaults. You can
also pass in the arguments explicitly:

fig = plt.figure((3,3))
fig.subplots_adjust(left=0.2, bottom=0.2)
ax = fig.add_subplot(111)
ax.plot(something)

ax.set_xlabel('test', fontsize=10)
for label in ax.get_xticklabels() + ax.get_yticklabels():
    label.set_fontsize(8)

plt.show()

If you do want to change the defaults via matplotlibrc, though,
something to bear in mind is that you can have "per-directory" rc
files. So for example if you want your defaults to be changed for a
figures for publication, you can drop an rc file into the scripts
directory for that publication, and that will be used for that
directory only and will not affect the global defaults in
~/.matplotlib/matplotlibrc.

See http://matplotlib.sourceforge.net/users/customizing.html

JDH

···

On Wed, Jun 10, 2009 at 9:40 AM, Paul Anton Letnes<paul.anton.letnes@...287...> wrote:

Hm, I see. Thanks for an informative answer. I'll dig into my rcParams
and matplotlibrc then...

5

I don't mean to bother people with this question again, but has anyone implemented this auto-adjust feature that John was talking about? It would be nice not having to adjust matplotlib.rcParams['figure.subplot.left'] (and friends) in every plot script, or alternatively, through a clever hierarchy of matplotlibrc files.

By the way: kudos to matplotlib in every other respect!

Cheers
Paul

···

On 10. juni 2009, at 14.53, John Hunter wrote:

On Wed, Jun 10, 2009 at 1:58 AM, Paul Anton > Letnes<paul.anton.letnes@...287...> wrote:

This _must_ be a bug. Consider the following:
##############
import matplotlib

No it is not a bug -- mpl is doing what you tell it to do. Consider

figure()
subplot(111)
plot([1,2,3])
xlabel('hi mom', fontsize=100)

Each command has precise meaning -- the fig creates a figure using the
default size, the subplot occupies a fraction of that figure according
to the default ratios in the subplots_adjust parameters, and the
xlabel makes a label at an indicated physical size. You may not be
explicitly setting those sizes, but they are all defined via defaults
in the matplotlibrc. We try and make mpl do what you tell it to do,
not to try and out-smart you and do what we think you are telling it
to do.

Now I definitely support the idea that we should have a *feature* to
auto-adjust the subplots_adjust params and fontsizes so that it "just
works" more often. But this should be an optional feature so the user
who wants to express their intent clearly will not constantly be
stymied by mpl adjusting the sizes. Michael Droettboom has worked on
it and it is a difficult problem to get right.

JDH

6

Hi, I’d very much vote for such a feature, too. It’s absolutely not foolproof currently the way it is :frowning:

What I find weird, too, is that while everthing fits on the canvas for PDF output, the left side is cropped for PNG.
´

Best regards,

Daniel

2011/2/1 Paul Anton Letnes wrote:

···

On 10. juni 2009, at 14.53, John Hunter wrote:

On Wed, Jun 10, 2009 at 1:58 AM, Paul Anton > > > > Letnes wrote:

This must be a bug. Consider the following:
##############
import matplotlib

No it is not a bug – mpl is doing what you tell it to do. Consider

figure()
subplot(111)
plot([1,2,3])
xlabel(‘hi mom’, fontsize=100)

Each command has precise meaning – the fig creates a figure using the

default size, the subplot occupies a fraction of that figure according
to the default ratios in the subplots_adjust parameters, and the
xlabel makes a label at an indicated physical size. You may not be

explicitly setting those sizes, but they are all defined via defaults
in the matplotlibrc. We try and make mpl do what you tell it to do,
not to try and out-smart you and do what we think you are telling it

to do.

Now I definitely support the idea that we should have a feature to
auto-adjust the subplots_adjust params and fontsizes so that it “just
works” more often. But this should be an optional feature so the user

who wants to express their intent clearly will not constantly be
stymied by mpl adjusting the sizes. Michael Droettboom has worked on
it and it is a difficult problem to get right.

JDH

I don’t mean to bother people with this question again, but has anyone implemented this auto-adjust feature that John was talking about? It would be nice not having to adjust matplotlib.rcParams[‘figure.subplot.left’] (and friends) in every plot script, or alternatively, through a clever hierarchy of matplotlibrc files.

By the way: kudos to matplotlib in every other respect!

Cheers
Paul