matplotlib 进阶之Tight Layout guide

简单的例子
Use with GridSpec
Legend and Annotations
Use with AxesGrid1
Colorbar
函数链接

matplotlib教程学习笔记

如何使用tight_layout？

tight_layout作用于ticklabels, axis, labels, titles等Artist

简单的例子

import matplotlib.pyplot as plt

import numpy as np

下面的例子和constrained_layout中的是一样的，notebook没有显示出其中的问题，就是labels被遮挡了

plt.rcParams['savefig.facecolor'] = "0.8"

def example_plot(ax, fontsize=12):

    ax.plot([1, 2])

    ax.locator_params(nbins=3)

    ax.set_xlabel('x-label', fontsize=fontsize)

    ax.set_ylabel('y-label', fontsize=fontsize)

    ax.set_title('Title', fontsize=fontsize)

plt.close('all')

fig, ax = plt.subplots()

example_plot(ax, fontsize=24)

fig, ax = plt.subplots()

example_plot(ax, fontsize=24)

plt.tight_layout()

注意到，每次作图，我们都需要通过使用plt.tight_layout()函数来激活，我们也可以通过

fig.set_tight_layout(True)使得每次作图都会自动tight布局，当然，还可以通过将

figure.autolayout rcParam设置为True来实现。

有多个plots的时候，会出现重叠的现象，通过tight_layout可以解决

plt.close('all')

fig, ((ax1, ax2), (ax3, ax4)) = plt.subplots(nrows=2, ncols=2)

example_plot(ax1)

example_plot(ax2)

example_plot(ax3)

example_plot(ax4)

fig, ((ax1, ax2), (ax3, ax4)) = plt.subplots(nrows=2, ncols=2)

example_plot(ax1)

example_plot(ax2)

example_plot(ax3)

example_plot(ax4)

plt.tight_layout()

tight_layout可以通过参数pad, w_pad, h_pad来设置一些布局的细节

fig, ((ax1, ax2), (ax3, ax4)) = plt.subplots(nrows=2, ncols=2)

example_plot(ax1)

example_plot(ax2)

example_plot(ax3)

example_plot(ax4)

plt.tight_layout(pad=0.4, w_pad=0.5, h_pad=2)

即使subplots的大小不一致，tight_layout依旧能够工作

plt.close('all')

fig = plt.figure()

ax1 = plt.subplot(221)

ax2 = plt.subplot(223)

ax3 = plt.subplot(122)

example_plot(ax1)

example_plot(ax2)

example_plot(ax3)

plt.tight_layout()

对subplot2grid也有效，注意subplot2grid参数为:

shape: e.g. (3, 3) 表示\(3 \times 3\)个格子

loc: e.g. (0, 1) 表示从第一行第二列个格子开始

rowspan: 跨行

colspan: 跨列

plt.close('all')

fig = plt.figure()

ax1 = plt.subplot2grid((3, 3), (0, 0))

ax2 = plt.subplot2grid((3, 3), (0, 1), colspan=2)

ax3 = plt.subplot2grid((3, 3), (1, 0), colspan=2, rowspan=2)

ax4 = plt.subplot2grid((3, 3), (1, 2), rowspan=2)

example_plot(ax1)

example_plot(ax2)

example_plot(ax3)

example_plot(ax4)

plt.tight_layout()

arr = np.arange(100).reshape((10, 10))

plt.close('all')

fig = plt.figure(figsize=(5, 4))

ax = plt.subplot(111)

im = ax.imshow(arr, interpolation="none")

plt.tight_layout()

Use with GridSpec

Gridspec 拥有自己的tight_layout()方法，当然，plt.tight_layout也是有效的

import matplotlib.gridspec as gridspec

plt.close('all')

fig = plt.figure()

gs1 = gridspec.GridSpec(2, 1)

ax1 = fig.add_subplot(gs1[0])

ax2 = fig.add_subplot(gs1[1])

example_plot(ax1)

example_plot(ax2)

gs1.tight_layout(fig)

gs.tight_layout提供rect参数，表示一个外界的框框

默认是(0, 0, 1, 1)

(x1, y1, x2, y2)

(x1, y1)矩形限制框左下角点

(x2, y2)矩形限制框右上角点

fig = plt.figure()

gs1 = gridspec.GridSpec(2, 1)

ax1 = fig.add_subplot(gs1[0])

ax2 = fig.add_subplot(gs1[1])

example_plot(ax1)

example_plot(ax2)

gs1.tight_layout(fig, rect=[0, 0, 0.5, 1])

这个功能可以很好的用在分割图形，以及分块操作上

fig = plt.figure()

gs1 = gridspec.GridSpec(2, 1)

ax1 = fig.add_subplot(gs1[0])

ax2 = fig.add_subplot(gs1[1])

example_plot(ax1)

example_plot(ax2)

gs1.tight_layout(fig, rect=[0, 0, 0.5, 1])

gs2 = gridspec.GridSpec(3, 1)

for ss in gs2:

    ax = fig.add_subplot(ss)

    example_plot(ax)

    ax.set_title("")

    ax.set_xlabel("")

ax.set_xlabel("x-label", fontsize=12)

gs2.tight_layout(fig, rect=[0.5, 0, 1, 1], h_pad=0.5)

# We may try to match the top and bottom of two grids ::

#为了让俩块图形上下一致，需要进行下面的操作

top = min(gs1.top, gs2.top)

bottom = max(gs1.bottom, gs2.bottom)

gs1.update(top=top, bottom=bottom)

gs2.update(top=top, bottom=bottom)

plt.show()

但是呢，Title和右边的边边不齐，所以框框是不包含title的？

fig = plt.gcf()

gs1 = gridspec.GridSpec(2, 1)

ax1 = fig.add_subplot(gs1[0])

ax2 = fig.add_subplot(gs1[1])

example_plot(ax1)

example_plot(ax2)

gs1.tight_layout(fig, rect=[0, 0, 0.5, 1])

gs2 = gridspec.GridSpec(3, 1)

for ss in gs2:

    ax = fig.add_subplot(ss)

    example_plot(ax)

    ax.set_title("")

    ax.set_xlabel("")

ax.set_xlabel("x-label", fontsize=12)

gs2.tight_layout(fig, rect=[0.5, 0, 1, 1], h_pad=0.5)

top = min(gs1.top, gs2.top)

bottom = max(gs1.bottom, gs2.bottom)

gs1.update(top=top, bottom=bottom)

gs2.update(top=top, bottom=bottom)

top = min(gs1.top, gs2.top)

bottom = max(gs1.bottom, gs2.bottom)

gs1.tight_layout(fig, rect=[None, 0 + (bottom-gs1.bottom),

                            0.5, 1 - (gs1.top-top)])

gs2.tight_layout(fig, rect=[0.5, 0 + (bottom-gs2.bottom),

                            None, 1 - (gs2.top-top)],

                 h_pad=0.5)

Legend and Annotations

fig, ax = plt.subplots(figsize=(4, 3))

lines = ax.plot(range(10), label='A simple plot')

ax.legend(bbox_to_anchor=(0.7, 0.5), loc='center left',)

fig.tight_layout()

plt.show()

有些时候，我们不希望legend也在tight_layout的掌控范围之内，这个时候，我们可以设置leg.set_in_layout(False)

fig, ax = plt.subplots(figsize=(4, 3))

lines = ax.plot(range(10), label='B simple plot')

leg = ax.legend(bbox_to_anchor=(0.7, 0.5), loc='center left',)

leg.set_in_layout(False)

fig.tight_layout()

plt.show()

Use with AxesGrid1

没看懂

from mpl_toolkits.axes_grid1 import Grid

plt.close('all')

fig = plt.figure()

grid = Grid(fig, rect=111, nrows_ncols=(2, 2),

            axes_pad=0.25, label_mode='L',

            )

for ax in grid:

    example_plot(ax)

ax.title.set_visible(False)

plt.tight_layout()

Colorbar

plt.close('all')

arr = np.arange(100).reshape((10, 10))

fig = plt.figure(figsize=(4, 4))

im = plt.imshow(arr, interpolation="none")

plt.colorbar(im, use_gridspec=True)

plt.close('all')

arr = np.arange(100).reshape((10, 10))

fig = plt.figure(figsize=(4, 4))

im = plt.imshow(arr, interpolation="none")

plt.colorbar(im, use_gridspec=True)

plt.tight_layout()

from mpl_toolkits.axes_grid1 import make_axes_locatable

plt.close('all')

arr = np.arange(100).reshape((10, 10))

fig = plt.figure(figsize=(4, 4))

im = plt.imshow(arr, interpolation="none")

divider = make_axes_locatable(plt.gca())

cax = divider.append_axes("right", "5%", pad="3%")

plt.colorbar(im, cax=cax)

plt.tight_layout()

函数链接

plt.tight_layout