Python 在 matplotlib 中保存子图
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原文地址: http://stackoverflow.com/questions/4325733/
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Save a subplot in matplotlib
提问by Robert Franke
Is it possible to save (to a png) an individual subplot in a matplotlib figure? Let's say I have
是否可以在 matplotlib 图中保存（到 png）单个子图？假设我有
import pyplot.matplotlib as plt
ax1 = plt.subplot(121)
ax2 = plt.subplot(122)
ax1.plot([1,2,3],[4,5,6])
ax2.plot([3,4,5],[7,8,9])
Is it possible to save each of the two subplots to different files or at least copy them separately to a new figure to save them?
是否可以将两个子图中的每一个保存到不同的文件中，或者至少将它们分别复制到一个新图形中以保存它们？
I am using version 1.0.0 of matplotlib on RHEL 5.
我在 RHEL 5 上使用 matplotlib 1.0.0 版。
Thanks,
谢谢，
Robert
罗伯特
采纳答案by Joe Kington
While @Eli is quite correct that there usually isn't much of a need to do it, it is possible. savefigtakes a bbox_inchesargument that can be used to selectively save only a portion of a figure to an image.
虽然@Eli 是非常正确的，通常不需要这样做，但这是可能的。 savefig接受一个bbox_inches参数，该参数可用于选择性地仅将图形的一部分保存到图像中。
Here's a quick example:
这是一个快速示例：
import matplotlib.pyplot as plt
import matplotlib as mpl
import numpy as np
# Make an example plot with two subplots...
fig = plt.figure()
ax1 = fig.add_subplot(2,1,1)
ax1.plot(range(10), 'b-')
ax2 = fig.add_subplot(2,1,2)
ax2.plot(range(20), 'r^')
# Save the full figure...
fig.savefig('full_figure.png')
# Save just the portion _inside_ the second axis's boundaries
extent = ax2.get_window_extent().transformed(fig.dpi_scale_trans.inverted())
fig.savefig('ax2_figure.png', bbox_inches=extent)
# Pad the saved area by 10% in the x-direction and 20% in the y-direction
fig.savefig('ax2_figure_expanded.png', bbox_inches=extent.expanded(1.1, 1.2))
The full figure:
完整图：
Area insidethe second subplot:
第二个子图内的区域：
Area around the second subplot padded by 10% in the x-direction and 20% in the y-direction:
第二个子图周围的区域在 x 方向填充 10%，在 y 方向填充 20%：
回答by Matt Gibson
Applying the full_extent()function in an answer by @Joe 3 years later from here, you can get exactly what the OP was looking for. Alternatively, you can use Axes.get_tightbbox()which gives a little tighter bounding box
full_extent()3 年后从这里开始在@Joe 的回答中应用该函数，您可以准确地获得 OP 正在寻找的内容。或者，您可以使用Axes.get_tightbbox()它提供更紧密的边界框
import matplotlib.pyplot as plt
import matplotlib as mpl
import numpy as np
from matplotlib.transforms import Bbox
def full_extent(ax, pad=0.0):
"""Get the full extent of an axes, including axes labels, tick labels, and
titles."""
# For text objects, we need to draw the figure first, otherwise the extents
# are undefined.
ax.figure.canvas.draw()
items = ax.get_xticklabels() + ax.get_yticklabels()
# items += [ax, ax.title, ax.xaxis.label, ax.yaxis.label]
items += [ax, ax.title]
bbox = Bbox.union([item.get_window_extent() for item in items])
return bbox.expanded(1.0 + pad, 1.0 + pad)
# Make an example plot with two subplots...
fig = plt.figure()
ax1 = fig.add_subplot(2,1,1)
ax1.plot(range(10), 'b-')
ax2 = fig.add_subplot(2,1,2)
ax2.plot(range(20), 'r^')
# Save the full figure...
fig.savefig('full_figure.png')
# Save just the portion _inside_ the second axis's boundaries
extent = full_extent(ax2).transformed(fig.dpi_scale_trans.inverted())
# Alternatively,
# extent = ax.get_tightbbox(fig.canvas.renderer).transformed(fig.dpi_scale_trans.inverted())
fig.savefig('ax2_figure.png', bbox_inches=extent)
I'd post a pic but I lack the reputation points
我会发布一张照片，但我缺乏声望点
