Axis font and exponent questions

Community matplotlib-users
1

Hi,

I have a few questions on formatting axis labels, when using the
ScalarFormatter class (which appears to be the basic standard).

Firstly, is there a general method to change the font size of all
labels on the axis, other than looping over them such as in:
>>> [x.set_fontsize(10) for x in plt.gca().xaxis.get_ticklabels()]

Secondly, when displaying the power limits with very large numbers on
the axis, how do you change the font size of the displayed power
limit? it does not seem to be tied into the axis ticklabels lists, and
I do not know how to access it.

Lastly, some questions on the defaults: The documentation mentions
that the default power limits were changed from (-3, 4) to (-7, 7).
I'm curious as to the reasoning for this, because 10^7 seems an
excessively large number of digits and altogether a much worse
default. In addition, the fact that using math text for the exponent
is turned off by default (displaying 1e3 instead of the much more
appropriate $10^3$) is also puzzling. In relation to this exponential
display, is there a better way to turn it on, on an existing plot,
other than the (seemingly undocumented):
>>> plt.gca().yaxis.get_major_formatter()._useMathText=True

Thanks!

Nick

2

Hi,

I have a few questions on formatting axis labels, when using the

ScalarFormatter class (which appears to be the basic standard).

Firstly, is there a general method to change the font size of all

labels on the axis, other than looping over them such as in:

[x.set_fontsize(10) for x in plt.gca().xaxis.get_ticklabels()]

If you have version 1.0.0 or later, you can use tick_params():

http://matplotlib.sourceforge.net/api/pyplot_api.html#matplotlib.pyplot.tick_params

http://matplotlib.sourceforge.net/api/axes_api.html#matplotlib.axes.Axes.tick_params

Secondly, when displaying the power limits with very large numbers on

the axis, how do you change the font size of the displayed power

limit? it does not seem to be tied into the axis ticklabels lists, and

I do not know how to access it.

Most likely, you are talking about the “offset text”, which you can get access to its Text object using:
ax.xaxis.get_offset_text() or ax.yaxis.get_offset_text()

Lastly, some questions on the defaults: The documentation mentions

that the default power limits were changed from (-3, 4) to (-7, 7).

I’m curious as to the reasoning for this, because 10^7 seems an

excessively large number of digits and altogether a much worse

default. In addition, the fact that using math text for the exponent

is turned off by default (displaying 1e3 instead of the much more

appropriate 10^3) is also puzzling. In relation to this exponential

display, is there a better way to turn it on, on an existing plot,

other than the (seemingly undocumented):

plt.gca().yaxis.get_major_formatter()._useMathText=True

I can’t comment on the change of the default range of values (that happened before I joined). However, there are two ways to get the nice MathText formatting of tick labels. One, you can change the axis scale to log:

ax.set_xscale(‘log’) or ax.set_yscale(‘log’)

Or (if you don’t want log scale), you can explicitly pass in a ScalarFormatter object with MathText turned on:

http://matplotlib.sourceforge.net/api/ticker_api.html#matplotlib.ticker.ScalarFormatter

niceMathTextForm = ScalarFormatter(useMathText=True)
ax.xaxis.set_major_formatter( niceMathTextForm )

I hope that helps!
Ben Root

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On Wed, Jan 19, 2011 at 9:16 AM, Nicholas Devenish <misnomer+matplotlib@…287…> wrote: