Use map.
假設T1 column叫A, T2 叫A同B
df1[“A”].map(df2.set_index(“A”)[“B”])
Note that個df2 A value一定要喺unique
亦可用merge,但冇map咁efficient
df.loc[:, [4, 5]] = df.loc[:, [5, 4]].to_numpy()
df.loc[:, [4, 5]] = df.loc[:, [5, 4]].to_numpy()
df[[4, 5]] = df[[4, 5]].astype(int)
df[[4, 5]] = df[[4, 5]].astype("Int64")
df = df.rename(columns={4:5, 5:4}).sort_index(axis=1)