Matplotlib 入门（二）：画图

一、散点图

   1、画几个散点一点都不难

将x,y放入plt.scatter()中就好了。

plt.scatter(np.arange(5),np.arange(5))  #绘制散点图

   2、代码

# -*- coding: utf-8 -*-"""Created on Sat Sep 23 19:20:54 2017@author: ryoyun"""# Scatter 散点图import matplotlib.pyplot as pltimport numpy as npn = 1024X = np.random.normal(0,1,n)Y = np.random.normal(0,1,n)#T = np.arctan2(Y,X) # for color value#plt.scatter(X,Y,s=75,c=T,alpha= 0.5)plt.scatter(np.arange(5),np.arange(5))  #绘制散点图#plt.xlim((-1.5,1.5))#plt.ylim((-1.5,1.5))plt.xticks(())plt.yticks(())plt.show()

   3、效果

二、柱状图

   1、柱状图生成

plt.bar(X, +Y1,facecolor='#9999ff',edgecolor='white') # 生成柱状图

   2、代码

# -*- coding: utf-8 -*-"""Created on Sat Sep 23 19:28:19 2017@author: ryoyun"""# bar 柱状图import matplotlib.pyplot as pltimport numpy as npn = 12X = np.arange(n)Y1 = (1- X/float(n))*np.random.uniform(0.5,1.0,n)Y2 = (1- X/float(n))*np.random.uniform(0.5,1.0,n)plt.bar(X, +Y1,facecolor='#9999ff',edgecolor='white') # 生成柱状图plt.bar(X, -Y2,facecolor='#ff9999',edgecolor='white')for x,y in zip(X,Y1):    # ha:horizontal alignment    plt.text(x+0.4,y+0.05,'%.2f'%y,ha ='center',va='bottom') # 数字标注for x,y in zip(X,Y2):    # ha:horizontal alignment    plt.text(x+0.4,-y-0.05,'-%.2f'%y,ha ='center',va='top')plt.xlim(-0.5,n)plt.xticks(())plt.ylim(-1.25,1.25)plt.yticks(())plt.show()

   3、效果

三、等高线

   1、三部曲

1.1轮廓填充

plt.contourf(X,Y,f(X,Y),8,alpha=0.75,cmap=plt.cm.hot)   # 填充轮廓

1.2画等高线

C = plt.contour(X,Y,f(X,Y),8,colors= 'black',linewidth = 0.5)   #画等高线

1.3进行标注

plt.clabel(C,inline= True ,fontsize= 10)        #增加标注

   2、代码

# -*- coding: utf-8 -*-"""Created on Sat Sep 23 19:44:25 2017@author: ryoyun"""# Contours 等高线图import matplotlib.pyplot as pltimport numpy as npdef f(x,y):    # the height function    return (1-x/2+x**5+y**3)*np.exp(-x**2-y**2)n = 256x = np.linspace(-3,3,n)y = np.linspace(-3,3,n)X,Y = np.meshgrid(x,y)  # 生成矩阵# plt.contourf to filling contours# X,Y and value for (X,Y) pointplt.contourf(X,Y,f(X,Y),8,alpha=0.75,cmap=plt.cm.hot)   # 填充轮廓# use plt.counter to add counter linesC = plt.contour(X,Y,f(X,Y),8,colors= 'black',linewidth = 0.5)   #画等高线# add labelplt.clabel(C,inline= True ,fontsize= 10)        #增加标注plt.xticks(())plt.yticks(())plt.show()

   3、效果

四、图片

   1、数字用图片来表示

plt.imshow(a,interpolation='nearest',cmap='bone',origin='lower')

a = 填充的数组

cmap='bone' #灰度色图

   2、代码

# -*- coding: utf-8 -*-"""Created on Sat Sep 23 19:57:52 2017@author: ryoyun"""# image 图片import matplotlib.pyplot as pltimport numpy as npn = 9#a = [[0 1 2]#    [3 4 5]#    [6 7 8]]a = np.array(np.arange(n)).reshape(3,3)# 生成3个数组，每个数组个元素plt.imshow(a,interpolation='nearest',cmap='bone',origin='lower')plt.colorbar()# 颜色标注plt.xticks(())plt.yticks(())plt.show()

   3、效果

五、3D视图

   1、更酷炫的3D图

1.1导入3d包

from mpl_toolkits.mplot3d import Axes3D

1.2增加3D的figure

ax = Axes3D(fig)

1.3 开始画3D图

ax.plot_surface(X,Y,Z,rstride= 1,cstride= 1,cmap=plt.get_cmap('rainbow'))

1.4 增加投影

ax.contourf(X,Y,Z,zdir='z',offset = -2,cmap='rainbow')

   2、代码

# -*- coding: utf-8 -*-"""Created on Sat Sep 23 20:09:50 2017@author: ryoyun"""# 3Dimport matplotlib.pyplot as pltimport numpy as npfrom mpl_toolkits.mplot3d import Axes3Dfig = plt.figure()ax = Axes3D(fig)# X,Y valueX = np.arange(-4,4,0.25)Y = np.arange(-4,4,0.25)X,Y = np.meshgrid(X,Y)      # 生成网格矩阵R = np.sqrt(X**2+Y**2)      # height valueZ = np.sin(R)               # z的值# rstride，cstride跨度# cmap=plt.get_cmap('rainbow') 颜色设置ax.plot_surface(X,Y,Z,rstride= 1,cstride= 1,cmap=plt.get_cmap('rainbow'))ax.contourf(X,Y,Z,zdir='z',offset = -2,cmap='rainbow')ax.set_zlim(-2,2)plt.show()

   3、效果

参考：莫烦python                 https://morvanzhou.github.io/tutorials/