Code Sample, a copy-pastable example if possible
df = pd.DataFrame({'c1': [1, 2, 3], 'c2': [3, 4, 5]})
df['c3'] = df['c1'] / df['c2']
df['c3'][0] = 0
I haven't tested with other arithmetic operators but I'm guessing it would happen for them as well.
Comment From: ZhuBaohe
use df.loc[0,'c3'] = 99
Comment From: jamesqo
@ZhuBaohe loc is kind of slow though. I'm just curious why this warning happpens in the first place
Comment From: ZhuBaohe
See Why does assignment fail when using chained indexing?
Comment From: jreback
this is well documented, you are doing chained indexing.