python - 尝试按城市将数据从 csv 导出到文本

Question

我正在尝试使用 python 将按城市分组的不同年份的数据从 csv 导出到文本文件，但我不确定如何去做

有一个csv文件例如

year    rainfall   city
2019      20         A
2019      10         B
2018      18         A
2018       9         B

import pandas as pd #used for other function in program
data = pd.read_csv(file.csv)
...
city=[]
for col in csv.columns:
   if "city" in col.lower():
   citylist = list(csv[col])
      for ct in citylist:
         if ct not in city:
           city.append(ct)

for numcity in city
    textfile= open(file.txt,"w")
    textfile.write()
    textfile.close

The outcome trying to achieve

A.txt
year   rainfall   city
2019      20        A
2018      18        A

B.txt
year   rainfall   city
2019      10        A
2018       9        A

Answer 1

如果需要按城市拆分dataframe，可以使用groupby:

for city, grp in data.groupby("city"):
    grp.to_csv(city + ".txt", index=False, sep="\t")