Build a Weather Query App with PyQt5 and Python: A Practical Guide

Development Environment

Python 3, PyQt5, and the requests library are required.

Data Preprocessing

City codes are obtained from https://www.heweather.com/documents/city.html as a CSV file. Using pandas, the CSV is read and only the 'City_ID' and 'City_CN' columns are kept. A regex function extracts the numeric part of each City_ID. A dictionary mapping Chinese city names to their numeric codes is built and saved as a JSON text file (city_code.txt) for fast lookup at runtime.

import pandas as pd
# 将下载好的文件命名为 'city_code.csv'
file = pd.read_csv('city_code.csv')
# 选取需要的两列信息
file = file.loc[:,['City_ID', 'City_CN']]
# 读取前五行信息
file.head()

# 匹配 City_ID 中的数字
def convert(x):
    pat = re.compile('(\d+)')
    return pat.search(x).group()

file['City_ID_map'] = file['City_ID'].map(convert)

# 建立城市与代码之间的映射关系
def city2id(file):
    code_dict = {}
    key = 'City_CN'
    value = 'City_ID_map'
    for k, v in zip(file[key], file[value]):
        code_dict[k] = v
    return code_dict

code_dict = city2id(file)

# 将所得的字典数据存储为 txt 文件
import json
filename = 'city_code.txt'
with open(filename, 'w') as f:
    json.dump(code_dict, f)

At runtime, the dictionary is loaded with:

with open(filename, 'r') as f:
    text = json.load(f)

UI Design

The interface is created with Qt Designer, featuring a line edit for city input, a query button, and a read-only text edit for displaying results. The generated UI file (Ui_weather.py) can be used directly.

Main Logic: Weather API Integration

The app uses the eTouch weather API: http://wthrcdn.etouch.cn/weather_mini?citykey={code}. The query_weather function sends a GET request, handles connection errors and JSON decode errors, and returns either the parsed weather information or an error message.

def query_weather(code):
    # 模板网页
    html = f'http://wthrcdn.etouch.cn/weather_mini?citykey={code}'
    # 向网页发起请求
    try:
        info = requests.get(html)
        info.encoding = 'utf-8'
    except requests.ConnectionError:
        raise
    # 将获取的数据转换为 json 格式
    try:
        info_json = info.json()
    except JSONDecodeError:
        return '无法查询'
    # 天气情况
    data = info_json['data']
    city = f"城市：{data['city']}
"
    today = data['forecast'][0]
    date = f"日期：{today['date']}
"
    now = f"实时温度：{data['wendu']}度
"
    temperature = f"温度：{today['high']} {today['low']}
"
    fengxiang = f"风向：{today['fengxiang']}
"
    type = f"天气：{today['type']}
"
    tips = f"贴士：{data['ganmao']}
"
    return city + date + now + temperature + fengxiang + type + tips

PyQt5 Widget Methods

Key widget interactions:

# 将 textEdit 设置为只读模式
self.textEdit.setReadOnly(True)
# 将鼠标焦点放在 lineEdit 编辑栏里
self.lineEdit.setFocus()
# 获取 lineEdit 中的文本
city = self.lineEdit.text()
# 设置文本
self.textEdit.setText(info)
# 清空文本
self.lineEdit.clear()

Key Press Event for Enter Key

Pressing Enter triggers the query:

def keyPressEvent(self, e):
    # 设置快捷键
    if e.key() == Qt.Key_Return:
        self.queryWeather()

Packaging

Create a standalone executable with pyinstaller -w weather.py. After building, copy city_code.txt into the dist/weather folder; otherwise the program cannot find the city code mapping and will fail to run.