在DataFrame的开头（最左端）插入一列

Dataframe.insert

df = pd.Dataframe({'A': ['x'] * 3, 'B': ['x'] * 3})df   A  B0  x  x1  x  x2  x  xseq = ['a', 'b', 'c']# This works in-place.df.insert(0, 'C', seq)df   C  A  B0  a  x  x1  b  x  x2  c  x  x

pd.concat

df = pd.concat([pd.Series(seq, index=df.index, name='C'), df], axis=1)df   C  A  B0  a  x  x1  b  x  x2  c  x  x

Dataframe.reindex

assign

df.reindex(['C', *df.columns], axis=1).assign(C=seq)   C  A  B0  a  x  x1  b  x  x2  c  x  x