10 / 10 Pandas Core

The Swap That Never Happened

A cleanup script tries to swap two columns in place.

df = pd.DataFrame({"A": [1, 2], "B": [10, 20]})
df.loc[:, ["B", "A"]] = df[["A", "B"]]
print(df.to_dict("list"))

What prints?

A

ValueError: Columns must be same length as key

B

{'A': [1, 2], 'B': [10, 20]}

C

{'A': [10, 20], 'B': [1, 2]}

D

{'A': [1, 2], 'B': [1, 2]}