import os
import pandas as pd

os.chdir(r'F:\ant_python\代码03_Python使用Pandas入门数据分析\ant-learn-pandas')
df = pd.read_csv("./datas/beijing_tianqi/beijing_tianqi_2017-2019.csv")

'''
# df['yWendu'] = df['yWendu'].str.replace('℃','').astype(int) # 反复运行会报错
# AttributeError: Can only use .str accessor with string values!
# df.apply(my_func,axis=1) # 不加result_type='expand'，仅返回元组

'''

df['bWendu'] = df['bWendu'].apply(lambda x :int(str(x).replace('℃','')))
df['yWendu'] = df['yWendu'].apply(lambda x :int(str(x).replace('℃','')))

df.head()

def my_func(row):
    return row['bWendu']- row['yWendu'],(row['bWendu']+ row['yWendu'])/2

df[['wencha','avg']] = df.apply(my_func,axis=1,result_type='expand')

df.head()