DataFrame.insert
df = pd.DataFrame({'A': ['x'] * 3, 'B': ['x'] * 3})
df
A B
0 x x
1 x x
2 x x
seq = ['a', 'b', 'c']
# This works in-place.
df.insert(0, 'C', seq)
df
C A B
0 a x x
1 b x x
2 c x x
pd.concat
df = pd.concat([pd.Series(seq, index=df.index, name='C'), df], axis=1)
df
C A B
0 a x x
1 b x x
2 c x x
DataFrame.reindex
+ assign
Reindex first, then assign will remember the position of the original column.
df.reindex(['C', *df.columns], axis=1).assign(C=seq)
C A B
0 a x x
1 b x x
2 c x x
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…