Python从网络接口爬取json天气预报数据绘制高温低温双折线图
实现一个功能，从网络上的天气预报接口读取天气预报中的json数据，json数据中包含高温和低温以及日期，然后把日期作为横坐标，高温和低温分别做两条折线绘制在同一张图上。
第一步，需要从网路接口中读取json天气预报数据并解析json中包含的高温、低温数据以及对应的日期。本例中的天气预报json数据接口：http:///api/weather/city/101270101
读出来的json数据格式如下所示：
{
"time": "2019-03-13 13:13:28",
"cityInfo": {
"city": "成都市",
"cityId": "101270101",
"parent": "四川",
"updateTime": "12:39"
},
"date": "20190313",
"message": "Success !",
"status": 200,
"data": {
"shidu": "64%",
"pm25": 83.0,
"pm10": 139.0,
"quality": "轻度污染",
"wendu": "14",
"ganmao": "儿童、老年人及心脏、呼吸系统疾病患者人群应减少长时间或高强度户外锻炼",
"yesterday": {
"date": "12",
"sunrise": "07:20",
"high": "高温 17.0℃",
"low": "低温 11.0℃",
"sunset": "19:09",
"aqi": 114.0,
"ymd": "2019-03-12",
"week": "星期二",
"fx": "无持续风向",
"fl": "<3级",
"type": "阵雨",
"notice": "阵雨来袭，出门记得带伞"
},
"forecast": [{
"date": "13",
"sunrise": "07:19",
"high": "高温 17.0℃",
"low": "低温 11.0℃",
"sunset": "19:10",
"aqi": 110.0,
"ymd": "2019-03-13",
"week": "星期三",
"fx": "无持续风向",
"fl": "<3级",
"type": "阵雨",
"notice": "阵雨来袭，出门记得带伞"
}, {
"date": "14",
"sunrise": "07:17",
"high": "高温 18.0℃",
"low": "低温 11.0℃",
"sunset": "19:11",
"aqi": 58.0,
"ymd": "2019-03-14",
"week": "星期四",
"fx": "无持续风向",
"fl": "<3级",
"type": "多云",
"notice": "阴晴之间，谨防紫外线侵扰"
}, {
"date": "15",
"sunrise": "07:16",
"high": "高温 14.0℃",
"low": "低温 9.0℃",
"sunset": "19:11",
"aqi": 66.0,
"ymd": "2019-03-15",
"week": "星期五",
"fx": "无持续风向",
"fl": "<3级",
"type": "小雨",
"notice": "雨虽小，注意保暖别感冒"
}, {
"date": "16",
"sunrise": "07:15",
"high": "高温 12.0℃",
"low": "低温 10.0℃",
"sunset": "19:12",
"aqi": 52.0,
"ymd": "2019-03-16",
"week": "星期六",
"fx": "无持续风向",
"fl": "<3级",
"type": "小雨",
"notice": "雨虽小，注意保暖别感冒"
}, {
"date": "17",
"sunrise": "07:14",
"high": "高温 14.0℃",
"low": "低温 10.0℃",
"sunset": "19:13",
"aqi": 65.0,
"ymd": "2019-03-17",
"week": "星期日",
"fx": "无持续风向",
"fl": "<3级",
"type": "小雨",
"notice": "雨虽小，注意保暖别感冒"
}, {
"date": "18",
"sunrise": "07:13",
"high": "高温 15.0℃",
"low": "低温 11.0℃",
"sunset": "19:13",
"aqi": 69.0,
"ymd": "2019-03-18",
"week": "星期一",
"fx": "无持续风向",
"fl": "<3级",
"type": "多云",
"notice": "阴晴之间，谨防紫外线侵扰"
}, {
"date": "19",
"sunrise": "07:11",
"high": "高温 14.0℃",
"low": "低温 9.0℃",
"sunset": "19:14",
"ymd": "2019-03-19",
"week": "星期二",
"fx": "无持续风向",
"fl": "<3级",
"type": "小雨",
"notice": "雨虽小，注意保暖别感冒"
}, {
"date": "20",
"sunrise": "07:10",
"high": "高温 17.0℃",
"low": "低温 6.0℃",
"sunset": "19:15",
"ymd": "2019-03-20",
"week": "星期三",
"fx": "东北风",
"fl": "<3级",
"type": "阴",
"notice": "不要被阴云遮挡住好心情"
}, {
"date": "21",
"sunrise": "07:09",
"high": "高温 17.0℃",
"low": "低温 7.0℃",
"sunset": "19:15",
"ymd": "2019-03-21",
"week": "星期四",
"fx": "东南风",
"fl": "<3级",
"type": "阴",
"notice": "不要被阴云遮挡住好心情"
}, {
"date": "22",
"sunrise": "07:08",
"high": "高温 18.0℃",
"low": "低温 10.0℃",
"sunset": "19:16",
"ymd": "2019-03-22",
"week": "星期五",
"fx": "东风",
"fl": "<3级",
"type": "小雨",
"notice": "雨虽小，注意保暖别感冒"
}, {
"date": "23",
"sunrise": "07:06",
"high": "高温 21.0℃",
"low": "低温 11.0℃",
"sunset": "19:16",
"ymd": "2019-03-23",
"week": "星期六",
"fx": "东南风",
"fl": "<3级",
"type": "多云",
"notice": "阴晴之间，谨防紫外线侵扰"
}, {
"date": "24",
"sunrise": "07:05",
"high": "高温 19.0℃",
"low": "低温 12.0℃",
"sunset": "19:17",
"ymd": "2019-03-24",
"week": "星期日",
"fx": "东北风",
"fl": "<3级",
"type": "小雨",
"notice": "雨虽小，注意保暖别感冒"
}, {
"date": "25",
"sunrise": "07:04",
"high": "高温 18.0℃",
"low": "低温 12.0℃",
"sunset": "19:18",
"ymd": "2019-03-25",
"week": "星期一",
"fx": "东北风",
"fl": "<3级",
"type": "小雨",
"notice": "雨虽小，注意保暖别感冒"
}, {
"date": "26",
"sunrise": "07:03",
"high": "高温 20.0℃",
"low": "低温 12.0℃",
"sunset": "19:18",
"ymd": "2019-03-26",
"week": "星期二",
"fx": "东风",
"fl": "<3级",
"type": "小雨",
"notice": "雨虽小，注意保暖别感冒"
}, {
"date": "27",
"sunrise": "07:02",
"high": "高温 20.0℃",
"low": "低温 13.0℃",
"sunset": "19:19",
"ymd": "2019-03-27",
"week": "星期三",
"fx": "东南风",
"fl": "<3级",
"type": "阴",
"notice": "不要被阴云遮挡住好心情"
}]
}
}
第二步，高温，低温，日期数据具备后，开始绘制折线图。
程序代码如下所示：
import json
import urllib.request
import matplotlib
from matplotlib import pyplot as plt
from datetime import datetime
def get_weather_json_data():
#101270101，天气预报中成都的代码。
url = "http:///api/weather/city/101270101"
response = urllib.request.urlopen(url)
content = response.read().decode('utf-8')
return content
def get_forecast_data(content):
data = content["data"]
return data["forecast"]
#清洗数据。过滤℃
def get_pure_temperature(temp):
a, b = temp.split()
return b.strip().strip("℃")
def make_chart(high, low, date_time):
matplotlib.rc('font', family='SimHei', weight='bold')
plt.rcParams['axes.unicode_minus'] = False
x = range(len(date_time))
plt.plot(x, low, ms=10,marker='*', color='blue', alpha=0.5, label="低温")
plt.plot(x, high, ms=10,marker='o', color='red', alpha=0.5, label="高温")
plt.fill_between(x, low, high, facecolor='gray', alpha=0.1)
plt.title("2019年3月 - 温度变化", fontsize=15)
plt.xticks(x, date_time, rotation=20)
plt.xlabel('日期')
plt.ylabel('温度')
plt.grid() # 显示网格
plt.legend()
plt.show()
content = json.loads(get_weather_json_data())
data = get_forecast_data(content)
high, low, date_time = [], [], []
for obj in data:
h = obj["high"]
high.append(get_pure_temperature(h))
l = obj["low"]
low.append(get_pure_temperature(l))
date_time.append(obj["ymd"])
#取得高温低温和日期，开始绘折线图。
make_chart(high, low, date_time)
运行结果如图：
