python 的 matplotlib

本文会一直更新matplot的画图技巧，使用方法

matplotlib教程

matplotlib API

1、实例一

本实例展示了matplotlib画图的基本流程

import matplotlib.pyplot as plt
#  step 1 prepare data
x = [1,2,3,4]
y = [10,20,25,30]

#  step 2 create plot
fig = plt.figure()

# step 3 plot settings
ax = fig.add_subplot(2,2,1)
ax.plot(x, y, color='blue', linewidth=2)
ax.set_xlim(1,6.5)

bx = fig.add_subplot(2,1,2)
bx.scatter([2,4,6,5],
[3,7,20,4],
color = 'green',
marker= '*')

# step 4 plot imshow

plt.show()

# if you want to save
plt.savefig('foo.png')

结果

2、实例二

# -*- coding: utf-8 -*-
import numpy as np
import matplotlib .pyplot as plt
from scipy import interpolate
from scipy import optimize
x = [0.01, 0.05, 0.08 , 0.1 ,0.2,0.4, 0.8, 1, 1.24,1.53,2]
y = [97.723, 97.456, 98.346, 99.124, 99.234, 98.5,98.43, 97.71,97.4, 97.24,97.20]

x1 = [0.01,  0.08 , 0.1 ,0.2,0.4, 1, 1.24,1.53,2]
y1 = [97.723, 98.346, 99.124, 99.234, 98.5, 97.71,97.4, 97.24,97.20]

t1 = [0.05, 97.456]
t2 = [0.8, 98.43]

fig = plt.figure()

img = fig.add_subplot(111)
img.plot(x,y,color="blue",linewidth=1)
img.plot(x1,y1,'k^')

xnew = np.linspace(min(x),max(x),300)

f2 = interpolate.interp1d(x,y,kind=2)
plt.plot(xnew, f2(xnew),'-.',color="green")

img.set_title("the sensitiveness of hyper parameter $\lambda$",size=14)#r'$\lambda$'
img.set_xlabel('$\lambda$' + '- type:float',size=12)
img.set_ylabel('Verfication on LFW Accuracy(%)',size=12)
img.set_ylim(96,100)
plt.grid(True)

plt.scatter([t1[0],],[t1[1],], 30, color='red')
plt.scatter([t2[0],],[t2[1],], 30, color='red')

plt.annotate(r'A(0.05, 97.456)',
t1, xycoords='data',
xytext=(-15,-30), textcoords='offset points', fontsize=12,
arrowprops=dict(arrowstyle="->", connectionstyle="arc3,rad=.2"))

plt.annotate(r'B(0.8, 98.43)',
t2, xycoords='data',
xytext=(+40,+40), textcoords='offset points', fontsize=12,
arrowprops=dict(arrowstyle="->", connectionstyle="arc3,rad=.2"))

plt.legend(['Linear','data','cubic smooth','key point'],loc='lower right',ncol=2)

plt.show()

结果

3、一些查表的参数

3.1.1 颜色& 线形

1、颜色

character	color
‘b’	blue
‘g’	green
‘r’	red
‘c’	cyan
‘m’	magenta
‘y’	yellow
‘k’	black
‘w’	white

2、线形

character	description
‘-‘	solid line style
‘–’	dashed line style
‘-.’	dash-dot line style
‘:’	dotted line style
‘.’	point marker
‘,’	pixel marker
‘o’	circle marker
‘v’	triangle_down marker
‘^’	triangle_up marker
‘<’	triangle_left marker
’s’	square marker
‘p’	pentagon marker
‘x’	x marker
‘D’	diamond marker
‘_’	hline marker

tip-颜色和线形可随意搭配。 ‘b^’ 或‘g>’或 ”bo”

3.1.2 x 轴显示

rotation=30, 可以用于x轴的标注

3.2

小写希腊字母