python学习笔记（二）绘图和可视化：matplotlib与Pandas

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matplotlib

官方资料：https://matplotlib.org/gallery/index.html

• 创建

1. 先创建figure对象（设置figsize）
2. 再创建subplot（设置图表布局）
3. 绘图

import matplotlib.pyplot as plt
from numpy.random import randn
fig = plt.figure(figsize = (10,5)) #1
ax1 = fig.add_subplot(2,2,1) #2
ax1.plot(randn(50).cumsum(),'k--') #3

图1

※ 由于根据特定布局创建figure和subplot是常见任务，所以可用plt.subplots()创建，返回一个figure对象和一组subplot对象
https://matplotlib.org/devdocs/api/_as_gen/matplotlib.pyplot.subplots.html

import matplotlib.pyplot as plt
from numpy.random import randn

#创建一个figure和一个subplot
fig2, axes = plt.subplots()
axes.plot(randn(50).cumsum(),'k--')

#创建一个figure和一行/列subplot
fig3, axes = plt.subplots(1, 2, sharey = True)
axes[0].plot(randn(50).cumsum(),'k--')
axes[1].plot(randn(50).cumsum(),'o--')

#创建一个figure和多个subplot
fig4, axes = plt.subplots(2, 2, sharey = True)
axes[0,1].plot(randn(50).cumsum(),'k--')
axes[1,0].plot(randn(50).cumsum(),'o--')

• 其他

调整subplot周围间距

plt.subplots_adjust(wspace = 0, hspace = 0) #注：轴标签会重叠，需要再调整

调整颜色、标记和线型
https://matplotlib.org/devdocs/api/_as_gen/matplotlib.pyplot.plot.html#matplotlib.pyplot.plot

Matplotlib recognizes the following formats to specify a color:

• an RGB or RGBA tuple of float values in [0, 1] (e.g., (0.1, 0.2, 0.5) or (0.1, 0.2, 0.5, 0.3));
• a hex RGB or RGBA string (e.g., '#0F0F0F' or '#0F0F0F0F');
• a string representation of a float value in [0, 1] inclusive for gray level (e.g., '0.5');
• one of {'b', 'g', 'r', 'c', 'm', 'y', 'k', 'w'};
• a X11/CSS4 color name;
• a name from the xkcd color survey; prefixed >with 'xkcd:' (e.g., 'xkcd:sky blue');
• one of {'tab:blue', 'tab:orange', 'tab:green', 'tab:red', 'tab:purple', 'tab:brown', 'tab:pink', 'tab:gray','tab:olive', 'tab:cyan'} which are the Tableau Colors from the 'T10' categorical palette (which is the default color cycle);
• a "CN" color spec, i.e. 'C' followed by a single digit, which is an index into the default property cycle (matplotlib.rcParams['axes.prop_cycle']); the indexing occurs at artist creation time and defaults to black if the cycle does not include color.

Set the linestyle of the line (also accepts drawstyles, e.g., 'steps--')

linestyle	description
'-' or 'solid'	solid line
'--' or 'dashed'	dashed line
'-.' or 'dashdot'	dash-dotted line
':' or 'dotted'	dotted line
'None'	draw nothing
' '	draw nothing
''	draw nothing

Markers
https://matplotlib.org/devdocs/api/markers_api.html#module-matplotlib.markers

调整刻度、标签和图例、注解（略）