Python Pandas：将所有其他列值附加到前3列

Question

I am trying to append all column values to the first three columns couldn't able to find any approach.

Input:

cv              cv      new_col       mg                mg  new_col sa              sa   new_col
5g              5g      cv            0% zinsen         zin mg      a-series-owner  ase  sa
2xopticalcam2x  zoom     cv           24 hour battery   hba mg      all             all  sa

Expected OutPut:

cv          cv   new_col        
5g              5g       cv           
2xopticalcam2x  zoom     cv           
0% zinsen       zin      mg
24 hour battery hba      mg
a-series-owner  ase      sa
all             all      sa

my approach:

oneCol = []
colLength = len(df)
for k in range(colLength):
    oneCol.append(df[k])

combined = pd.concat(oneCol, ignore_index=True)

print(combined)

but I am not getting the expected output.

Answer 1

IIUC

step = 3
df = pd.concat([pd.DataFrame(df.iloc[:, x:x+step].values)\
                             for x in range(0, len(df.columns), step)], 
               sort=True, 
               ignore_index=True)

---

                 0     1   2
0               5g    5g  cv
1   2xopticalcam2x  zoom  cv
2        0% zinsen   zin  mg
3  24 hour battery   hba  mg
4   a-series-owner   ase  sa
5              all   all  sa

Answer 2

You can change previous answer with creating default columns names by DataFrame.set_axis :

df = pd.concat([v.set_axis(range(len(v.columns)), inplace=False, axis=1).assign(new_col=k)
                 for k, v in df.groupby(axis=1, level=0)], axis=0)

---

Or if always 3 values per groups:

df1 = pd.DataFrame(df.values.reshape(-1, 3))