Python：如何为熊猫数据框中的每个 ID 保存不同的 .csv？

Question

I have a dataframe df that looks like the following:

df
    ID    val
0    A     3
1    A     2
2    B     0
3    B     5 
4    B     4

I would like to save different dataframes for each users. This is what I am doing

for i in pd.unique(df['ID']):
      tmp = df[df['ID']==i]
      tmp.to_csv('%s.csv'%i)

However I have a very large dataframe and 14k ID. I would like to know if there is a better way to do it.

Answer 1

I think your solution is good, here is alternative:

for i, g in df.groupby('ID', sort=False):
    g.to_csv('{}.csv'.format(i), index=False)

Or solution with f-string s:

for i, g in df.groupby('ID', sort=False):
    g.to_csv(f'{i}.csv', index=False)