Python制作折线图

利用python的第三方包Pygal制作简单的折线图。
申明：本文仅供学习交流使用。源码大部分来自《python编程从入门到实践》；如有侵权，请联系我删除。
  1 #!usr/bin/env python3
  2 # -*-coding=utf-8 -*-
  3 '''
  4     制作一个简单的交易走势图。源码大部分来自<python编程从入门到实践>
  5     过程分析:
  6         1,从网站下载数据并存储到本地，两种方法:
  7             a,urlopen
  8             b,requests
  9         2,读取本地数据，利用pygal制作交易走势图
 10 '''
 11 #正文开始
 12 from __future__ import (absolute_import, division, print_function, unicode_literals)
 13 try:
 14     from urllib2 import urlopen
 15 except ImportError:
 16     from urllib.request import urlopen
 17 import json
 18 import requests
 19 import pygal
 20 from pygal.style import LightColorizedStyle as LCS,LightenStyle as LS
 21 
 22 #第一种方法利用urlopen提取网络上存储的数据
 23 #定义要提取数据的url
 24 URL = "https://www.xxx.com/btc_close_2017.json"
 25 read_url = urlopen(URL) #读取URL
 26 read_response = read_url.read() #读取返回的数据
 27 
 28 #开始存储数据到本地, 以'wb'形式(二进制)
 29 with open('btc_close_2017_urllib.json', 'wb') as file_object:
 30     file_object.write(read_response) #将读取到的数据写入到文件
 31 
 32 file_urllib = json.loads(read_response)
 33 print(file_urllib)
 34 
 35 #第二种方法利用requests提取网络上存储的数据
 36 #定义要提取数据的URL
 37 URL = "https://www.xxx.com/btc_close_2017.json"
 38 response = requests.get(URL) #利用requests读取URL并获取数据
 39 
 40 #开始存储数据到本地文件;
 41 with open('btc_close_2017_requests.json', 'w') as file_object:
 42     file_object.write(response.text) #写入数据到本地文件，要以str格式写入
 43 
 44 file_requests = response.json()
 45 print(file_requests)
 46 
 47 print("-----------------------I am delimiter-----------------")
 48 #打印一下两种方法是不是获取到相同的数据
 49 print(file_urllib == file_requests) #True
 50 
 51 #开始读取相关数据
 52 filename = 'btc_close_2017.json'; #加载文件
 53 
 54 #以读的方式打开文件
 55 with open(filename) as file_object:
 56     btc_data = json.load(file_object) #将读取到的数据加载为json格式
 57 
 58 print(btc_data) #打印是否符合预期
 59 
 60 #打印每一天的信息,并将字符串转换成数值型的:
 61 for btc_dict in btc_data:
 62     date = btc_dict['date']
 63     month = int(btc_dict['month'])
 64     week = int(btc_dict['week'])
 65     weekday = btc_dict['weekday']
 66     close_price = int(float(btc_dict['close'])) #先将字符串转换为浮点型,再将浮点型转换成整型
 67     print("{} is month: {}, week: {}, weekday: {}, the close price is: {}".format(date,month,week,weekday,close_price))
 68 
 69 
 70 #可视化,开始绘制收盘价折线图
 71 
 72 #定义空列表以存储循环得到的项
 73 dates, months, weeks, weekdays, close_prices = [], [], [], [], []
 74 #循环读取btc_data里的每一项
 75 for btc_dict in btc_data:
 76     date = btc_dict['date']
 77     month = int(btc_dict['month'])
 78     week = int(btc_dict['week'])
 79     weekday = btc_dict['weekday']
 80     close_price = int(float(btc_dict['close'])) #先将字符串转换为浮点型,再将浮点型转换成整型
 81 
 82     #将每一项追加到对应的空列表
 83     dates.append(date)
 84     months.append(month)
 85     weeks.append(week)
 86     weekdays.append(weekday)
 87     close_prices.append(close_price)
 88 
 89 line_chart = pygal.Line(x_label_rotation=20,show_minor_x_labels=False) #x轴标签顺时针旋转20度,show_minor_x_labels告诉pygal不必显示全部的x轴标签
 90 line_chart.title = "Close Price ($)" #标题
 91 line_chart.x_title = "Dates" #x轴标题
 92 line_chart.y_title = "Price" #y轴标题
 93 line_chart.x_labels = dates #x轴标签
 94 line_chart.x_labels_major = dates[::20] #让x轴坐标每隔20天显示第一次;
 95 line_chart.add("BTC", close_prices) #
 96 line_chart.render_to_file('closeprice.svg')
 97 
 98 '''
 99     写一些折线图的样式
100 '''
101 my_style = LS("#999888",base_style=LCS)
102 my_config = pygal.Config()
103 my_config.x_label_rotation = 20
104 my_config.show_legend = False
105 my_config.show_minor_x_labels = False
106 my_config.title_font_size = 10
107 my_config.label_font_size = 10
108 my_config.major_label_font_size = 18
109 my_config.truncate_label = 10
110 my_config.show_y_guides = False
111 my_config.width = 1000
112 
113 #利用样式可视化
114 line_chart = pygal.Line(my_config,style=my_style)
115 line_chart.title = "BTC close price in 2017"
116 line_chart.x_title = "Dates"
117 line_chart.y_title = "Price"
118 line_chart.x_labels = dates
119 line_chart.x_labels_major = dates[::20]
120 line_chart.add("SPJ",close_prices)
121 line_chart.render_to_file("closeprice1.svg")