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 plt
import numpy as np

n = 1024
X = 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 plt
import numpy as np

n = 12
X = 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 plt
import numpy as np

def f(x,y):
    # the height function
    return (1-x/2+x**5+y**3)*np.exp(-x**2-y**2)

n = 256
x = 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) point
plt.contourf(X,Y,f(X,Y),8,alpha=0.75,cmap=plt.cm.hot)   # 填充轮廓

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

# add label
plt.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 plt
import numpy as np
n = 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
"""

# 3D
import matplotlib.pyplot as plt
import numpy as np
from mpl_toolkits.mplot3d import Axes3D

fig = plt.figure()
ax = Axes3D(fig)

# X,Y value
X = 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 value
Z = 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/

来源：CSDN

作者：若云流风

链接：https://blog.csdn.net/u013584315/article/details/78076167

标签

matplotlib

等高线