[FIXED] add columns different length pandas

Issue

I have a problem with adding columns in pandas. I have DataFrame, dimensional is nxk. And in process I wiil need add columns with dimensional mx1, where m = [1,n], but I don't know m.

When I try do it:

df['Name column'] = data    
# type(data) = list

result:

AssertionError: Length of values does not match length of index   

Can I add columns with different length?

Solution

Use concat and pass axis=1 and ignore_index=True:

In [38]:

import numpy as np
df = pd.DataFrame({'a':np.arange(5)})
df1 = pd.DataFrame({'b':np.arange(4)})
print(df1)
df
   b
0  0
1  1
2  2
3  3
Out[38]:
   a
0  0
1  1
2  2
3  3
4  4
In [39]:

pd.concat([df,df1], ignore_index=True, axis=1)
Out[39]:
   0   1
0  0   0
1  1   1
2  2   2
3  3   3
4  4 NaN

Answered By - EdChum