df = pd.DataFrame({'a':[1,2,3,4],'b':[5,6,7,8],'c':[9,10,11,12]})
How can I insert a new row of zeros at index 0 in one single line?
I tried pd.concat([pd.DataFrame([[0,0,0]]),df) but it did not work.
The desired output:
a b c
0 0 0 0
1 1 5 9
2 2 6 10
3 3 7 11
4 4 8 12
You can concat the temp df with the original df but you need to pass the same column names so that it aligns in the concatenated df, additionally to get the index as you desire call reset_index with drop=True param.
In [87]:
pd.concat([pd.DataFrame([[0,0,0]], columns=df.columns),df]).reset_index(drop=True)
Out[87]:
a b c
0 0 0 0
1 1 5 9
2 2 6 10
3 3 7 11
4 4 8 12
alternatively to EdChum's solution you can do this:
In [163]: pd.DataFrame([[0,0,0]], columns=df.columns).append(df, ignore_index=True)
Out[163]:
a b c
0 0 0 0
1 1 5 9
2 2 6 10
3 3 7 11
4 4 8 12
An answer more specific to the dataframe being prepended to
pd.concat([df.iloc[[0], :] * 0, df]).reset_index(drop=True)
