CODEWITHSUNDEEP
pythonpandas
Ben C Wang
Ben C Wang

Reputation: 607

How to concat 2 pandas columns in separate position?

I have a dataframe like so:

df1:

col_1, col_2
a,1
b,2    
c,3
d,4

And I'd like to concat df1 twice with the 2 columns swapping positions so that I have:

col_a, col_b
a,1
b,2
c,3
d,4
1,a
2,b
3,c
4,d

I tried: 

df2 = pd.DataFrame(columns=['col_a','col_b'])
df2[['col_a','col_b']] = pd.concat([df1[['col_1','col_2]],df1[['col_2','col_1']]])

However, this just concats the dataframe against itself, so the result is:

col_a, col_b
a,1
b,2
c,3
d,4
a,1
b,2
c,3
d,4

What is the correct way to do this?

Upvotes: 0

Views: 80

Answers (2)

BENY
BENY

Reputation: 323226

From numpy 

pd.DataFrame(np.vstack([df.values,df.values[:,::-1]]),columns=df.columns)
Out[850]: 
  col_1 col_2
0     a     1
1     b     2
2     c     3
3     d     4
4     1     a
5     2     b
6     3     c
7     4     d

Upvotes: 0

rafaelc
rafaelc

Reputation: 59274

Using concat

x = pd.DataFrame(df.iloc[:, [1,0]].values, columns=df.columns)
pd.concat([df, x], sort=False)

    col_1   col_2
0   a       1
1   b       2
2   c       3
3   d       4
0   1       a
1   2       b
2   3       c
3   4       d

Upvotes: 2

Related Questions