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I would like to limit the X and Y axis in matplotlib for a specific subplot. The subplot figure itself doesn't have any axis property. I want for example to change only the limits for the second plot:

import matplotlib.pyplot as plt
fig=plt.subplot(131)
plt.scatter([1,2],[3,4])
fig=plt.subplot(132)
plt.scatter([10,20],[30,40])
fig=plt.subplot(133)
plt.scatter([15,23],[35,43])
plt.show()
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3
  • your question was not clear, I can think of may 4 or 5 ways to set up something this simple with sub-plots. Commented Apr 7, 2013 at 2:34
  • 3
    If you can think of setting up in 4 or 5 ways, it shows that you already understood the question in the first place. Commented Apr 7, 2013 at 2:36
  • 6
    Because, I suspected that you have some gaps in your understanding of the class hierarchy of of mpl (which your variable names confirm). Thus, you will benefit the most if I can show you how to adapt the code you already have. Commented Apr 7, 2013 at 2:50

1 Answer 1

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372

You should use the object-oriented interface to matplotlib, rather than the state machine interface. Almost all of the plt.* function are thin wrappers that basically do gca().*.

plt.subplot returns an axes object. Once you have a reference to the axes object you can plot directly to it, change its limits, etc.

import matplotlib.pyplot as plt

ax1 = plt.subplot(131)
ax1.scatter([1, 2], [3, 4])
ax1.set_xlim([0, 5])
ax1.set_ylim([0, 5])


ax2 = plt.subplot(132)
ax2.scatter([1, 2],[3, 4])
ax2.set_xlim([0, 5])
ax2.set_ylim([0, 5])

and so on for as many axes as you want.

Or better, wrap it all up in a loop:

import matplotlib.pyplot as plt

DATA_x = ([1, 2],
          [2, 3],
          [3, 4])

DATA_y = DATA_x[::-1]

XLIMS = [[0, 10]] * 3
YLIMS = [[0, 10]] * 3

for j, (x, y, xlim, ylim) in enumerate(zip(DATA_x, DATA_y, XLIMS, YLIMS)):
    ax = plt.subplot(1, 3, j + 1)
    ax.scatter(x, y)
    ax.set_xlim(xlim)
    ax.set_ylim(ylim)
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7 Comments

Problem with keeping the axis instance is that it does not have all the properties that plt has, for example one cannot use axis.ylim() to get the ylim of the plot on an axis.
@dashesy You use set_xlim and set_ylim. plt has many fewer options than working directly with the axes object. In fact, almost every function in plt is a very thin wrapper that first calls ax = plt.gca() and then calls what ever function on that object. You should not be using plt for anything but interactive work.
Yes, I agree, not relying on the interactive version is preferable, but there is no way to get the ylim of a plot having only axis. After a plot is done, it will have an automatic ylim assigned, but the axis will not have that information. So if latter drawings depend on the ylim, as you said one has to set_ylim to override the current range.
sorry, forgot about that bit of magic in plt.ylim. There is also a get_ylim() function on the axes which will return the limits and ax.get_yaxis() function which will return to you the axis (note difference between axes and axis). There are also the symmetric versions for the xaxis.
@aderchox because they are in different namespaces. plt.xlim and plt.ylim are in matplotlib.pyplot and ax.set_xlim and ax.set_ylim are methods on the Axes object. In almost all cases you should prefer to use the Axes methods rather than pyplot.
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