Python之Matplotlib.pyplot画图模块函数详解和使用_matplotlib.pyplot plot函数

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来源：https://zhuanlan.zhihu.com/p/258106097

plt.plot()函数是matplotlib.pyplot模块下的一个函数, 用于画图它可以绘制点和线, 并且对其样式进行控制。

我们经常用这个模块绘制神经网络模型训练和验证时绘制各种变化曲线，以查看训练情况，下面由浅入深对其介绍和绘制各种点线图、折线图、曲线图等。

plt.plot()函数介绍

图线绘制

1.pltplot(x, y)

1.1 x为x轴数据, y为y轴数据

import matplotlib.pyplot as plt
 
x=[3,4,5] # [列表]
y=[2,3,2] # x,y元素个数N应相同
plt.plot(x,y)
plt.show()

1.2 x, y可传入(元组), [列表], np.array, pd.Series

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
 
x=(3,4,5) # (元组)
y1=np.array([3,4,3]) # np.array
y2=pd.Series([4,5,4]) # pd.Series
 
plt.plot(x,y1)
plt.plot(y2)  # x可省略,默认[0,1..,N-1]递增
plt.show() # plt.show()前可加多个plt.plot(),画在同一张图上

1.3 可传入多组x, y

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
 
x=(3,4,5)
y1=np.array([3,4,3])
y2=pd.Series([4,5,4])
 
plt.plot(x,y1,x,y2) # 此时x不可省略
plt.show()

 

1.4 x或y传入pd.DataFrame

1.4.1 x, y可以不等长, x短

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
 
dic1={'x列0':[0,1,2],'x列1':[3,4,5]}
x=pd.DataFrame(dic1)
dic2={'y列0':[2,3,2],'y列1':[3,4,3],'y列2':[4,5,4],'y列3':[5,6,5]}
y=pd.DataFrame(dic2)
print(x)
print(y)
plt.plot(x,y)
plt.show()

x最短可为(元组), [列表], np.array, pd.Series

1.4.2 x, y可以不等长, x长

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
 
dic1={'x列0':[0,1,2],'x列1':[3,4,5],'x列2':[6,7,8],'x列3':[9,10,11]}
x=pd.DataFrame(dic1)
dic2={'y列0':[2,3,2],'y列1':[3,4,3]}
y=pd.DataFrame(dic2)
print(x)
print(y)
plt.plot(x,y)
plt.show()

y最短可为(元组), [列表], np.array, pd.Series

1.5 x或y传入二维数组

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
 
lst1=[[0,1,2],[3,4,5],[6,7,8]]
x=np.array(lst1)
lst2=[[2,3,2],[3,4,3],[4,5,4]]
y=np.array(lst2)
print(x)
print(y)
plt.plot(x,y)
plt.show()

2.plt.plot(x, y, "格式控制字符串")

点和线的格式可以用"格式控制字符串"设置

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
 
lst1=[[0,1,2],[3,4,5],[6,7,8]]
x=np.array(lst1)
lst2=[[2,3,2],[3,4,3],[4,5,4]]
y=np.array(lst2)
 
plt.plot(x,y,"ob:") #"b"为蓝色, "o"为圆点, ":"为点线
plt.show()

2.1 "格式控制字符串"最多可以包括三部分, "颜色", "点型", "线型"

2.1.1 "颜色"与"线型"

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
 
color=['b','g','r','c','m','y','k','w']
linestyle=['-','--','-.',':']
dic1=[[0,1,2],[3,4,5]]
x=pd.DataFrame(dic1)
dic2=[[2,3,2],[3,4,3],[4,5,4],[5,6,5]]
y=pd.DataFrame(dic2)
# 循环输出所有"颜色"与"线型"
for i in range(2):
    for j in range(4):
        plt.plot(x.loc[i],y.loc[j],color[i*4+j]+line_style[j]) 
plt.show()

2.1.2 "点型"

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
 
marker=['.',',','o','v','^','<','>','1','2','3','4','s','p','*','h','H','+','x','D','d','|','_','.',',']
dic1=[[0,1,2],[3,4,5],[6,7,8],[9,10,11],[12,13,14],[15,16,17]]
x=pd.DataFrame(dic1)
dic2=[[2,3,2.5],[3,4,3.5],[4,5,4.5],[5,6,5.5]]
y=pd.DataFrame(dic2)
# 循环输出所有"点型"
for i in range(6):
    for j in range(4):
        plt.plot(x.loc[i],y.loc[j],"b"+marker[i*4+j]+":") # "b"蓝色,":"点线
plt.show()

3.plt.plot(x, y, "格式控制字符串", 关键字=参数)

除了"格式控制字符串", 还可以在后面添加关键字=参数

import matplotlib.pyplot as plt
 
y=[2,3,2] 
# 蓝色,线宽20,圆点,点尺寸50,点填充红色,点边缘宽度6,点边缘灰色
plt.plot(y,color="blue",linewidth=20,marker="o",markersize=50,
         markerfacecolor="red",markeredgewidth=6,markeredgecolor="grey")
plt.show()

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