Python高级数据处理与可视化（二）---Matplotlib绘图基础

Matplotlib绘图基础

最著名Python绘图库，主要用于二维绘图

• 画图质量高
• 方便快捷的绘图模块
• 绘图API—–pyplot模块 工作方式类似Matlab
  集成库—–pylab模块（包含NumPy和pyplot中的常用函数） 偏重快速画图

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心形图

# -*- coding: utf-8 -*-
"""
Demo of a PathPatch object.
"""
import matplotlib.path as mpath
import matplotlib.patches as mpatches
import matplotlib.pyplot as plt


fig, ax = plt.subplots()

Path = mpath.Path
path_data = [
    (Path.MOVETO, (1.58, -2.57)),
    (Path.CURVE4, (0.35, -1.1)),
    (Path.CURVE4, (-1.75, 2.0)),
    (Path.CURVE4, (0.375, 2.0)),
    (Path.LINETO, (0.85, 1.15)),
    (Path.CURVE4, (2.2, 3.2)),
    (Path.CURVE4, (3, 0.05)),
    (Path.CURVE4, (2.0, -0.5)),
    (Path.CLOSEPOLY, (1.58, -2.57)),
    ]
codes, verts = zip(*path_data)
path = mpath.Path(verts, codes)
patch = mpatches.PathPatch(path, facecolor='r', alpha=0.5)
ax.add_patch(patch)

# plot control points and connecting lines
x, y = zip(*path.vertices)
line, = ax.plot(x, y, 'go-')

ax.grid()
ax.axis('equal')
plt.show()

path_patch_demo.py

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折线、散点、柱状图

实例1

• 将Cocacosla近一年来股票收盘价的月平均价绘制成折线图，散点图，直方图（括号中参数为列表）

import time 
from matplotlib.finance import quotes_historical_yahoo_ochl 
from datetime import date 
from datetime import datetime 
import pandas as pd 
import matplotlib.pyplot as plt     #导入pyplot模块

today = date.today() 
start = (today.year-1, today.month, today.day) 
quotes = quotes_historical_yahoo_ochl('KO', start, today) 
fields = ['date','open','close','high','low','volume']

list1 = [] 
for i in range(0,len(quotes)):
    x = date.fromordinal(int(quotes[i][0]))
    y = datetime.strftime(x,'%Y-%m-%d')
    list1.append(y) 
#print list1 
quoteskodf = pd.DataFrame(quotes, index = list1, columns = fields) 
quoteskodf = quoteskodf.drop(['date'], axis = 1) 
#print quotesdf 
listtemp = [] 
for i in range(0,len(quoteskodf)):
    temp = time.strptime(quoteskodf.index[i],"%Y-%m-%d")
    listtemp.append(temp.tm_mon)

print(listtemp) 
tempkodf = quoteskodf.copy() 
tempkodf['month'] = listtemp 
closeMeansKO = tempkodf.groupby('month').mean().close     #【可口可乐公司近一年来股票收盘价的月平均价】作为【数据源】  
listKO = [] 
for i in range(1,13):
    listKO.append(closeMeansKO[i])                      
listKOIndex = closeMeansKO.index 
plt.plot(listKOIndex,listKO) 
plt.plot(listKOIndex,listKO,'o')
plt.bar(listKOIndex,listKO)    

实例2

• Numpy数组也可作为Matplotlib的参数 和 pylab绘图

import numpy as np
import matplotlib.pyplot as plt

t = np.arange(0.,4.,0.1)
plt.plot(t,t,t,t+2,t,t**2)    #plot()参数只要是序列皆可，包括元组、列表、数组