1 matplotlib概述

matplotlib 是 Python 的绘图库。使用matplot可以方便地画出折线图、散点图、热力图、饼图等等

2 matplotlib安装

#pip pip install matplotlib #conda conda install matplotlib

3 matplotlib使用

3.1 查看信息

import matplotlib as mpl #打印版本信息 print(mpl.__version__)

3.2 简单折线图绘制

import matplotlib.pyplot as plt import numpy as np # 以下两行代码解决jupyter notebook显示图片模糊问题 %matplotlib inline %config InlineBackend.figure_format = 'svg' x = np.linspace(1,10) # y1=5+x y1=5+x plt.plot(x,y1) # y2=5+2*x y2=5+2*x plt.plot(x,y2) # 标题，支持中文 plt.title(u"简单折线图",fontproperties="SimHei") plt.xlabel("X") plt.ylabel("Y") plt.show()

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3.3 多图

import matplotlib.pyplot as plt import numpy as np # 以下两行代码解决jupyter notebook显示图片模糊问题 %matplotlib inline %config InlineBackend.figure_format = 'svg' # 多图，即创建多个画布 fig1 = plt.figure() fig2 = plt.figure() fig3 = plt.figure() # 由于画布上没有图，所以会显示空白 plt.show()

3.4子图

import matplotlib.pyplot as plt import numpy as np # 以下两行代码解决jupyter notebook显示图片模糊问题 %matplotlib inline %config InlineBackend.figure_format = 'svg' # 子图，即一个画布上画多个图 fig1 = plt.figure() sf1 = fig1.add_subplot(221) sf2 = fig1.add_subplot(222) sf3 = fig1.add_subplot(223) sf4 = fig1.add_subplot(224) x = np.linspace(0,10,100) y1 = x**2 y2 = -x**2 y3 = x y4 = -x # 绘图 sf1.plot(x,y1) sf1.set_xlabel('X') sf1.set_ylabel('Y') sf1.set_title('fig1') sf2.plot(x,y2) sf2.set_xlabel('X') sf2.set_ylabel('Y') sf2.set_title('fig2') sf3.plot(x,y3) sf3.set_xlabel('X') sf3.set_ylabel('Y') sf3.set_title('fig3') sf4.plot(x,y4) sf4.set_xlabel('X') sf4.set_ylabel('Y') sf4.set_title('fig4') plt.subplots_adjust(wspace =0.4, hspace =0.6)#调整子图间距 plt.show()

3.5 散点图

x = np.linspace(1, 10, 100) y = np.sin(x) # 散点图 scatter plt.scatter(x, y) plt.title('sin(x)') plt.show()

3.6 直方图

#直方图 x = np.random.randn(100) # density = True 纵坐标归一化 bins=3表示三条柱子 plt.hist(x,density=True,bins=3) plt.title("Hist") plt.show()

3.7饼状图

# 饼状图 x=[0.4,0.1,0.1,0.4] labels=["A","B","C","D"] # shadow=True：阴影 explode：突出显示的权重 plt.pie(x,labels=labels,shadow=True,explode=[0.1,0,0,0.2]) plt.show()

3.8 网格

import matplotlib.pyplot as plt plt.plot([1,2,3],[3,2,1]) plt.grid(color="red",linewidth=1) plt.show()

3.9 图例

import matplotlib.pyplot as plt import numpy as np x = np.linspace(1,10,1000) y1=x y2=x**2 y3=x**3 plt.plot(x,y1,label=["Y=X"]) plt.plot(x,y2,label=["Y=X**2"]) plt.plot(x,y3,label=["Y=X**3"]) # loc指定位置 0 1 2 3对应四个角 # ncol 指定图例分成几列 plt.legend(loc=0,ncol=2) plt.show()

4 案例

import matplotlib.pyplot as plt import numpy as np fig = plt.figure() ax1 = fig.add_subplot(221) ax2 = fig.add_subplot(222) ax3 = fig.add_subplot(212) X = np.linspace(-10,10,100) Y1=np.sin(X) Y2=np.tanh(X) Y3=np.sign(X) ax1.plot(X,Y1,"r--") ax2.plot(X,Y2,color="b",linestyle="-.",linewidth=2) ax3.plot(X,Y3,"g-",marker="o") plt.show()