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What does print(resultat, df['a'].tolist()) print? pandas Copy-on-Write, Views and Assignment
Block 7, Copy-on-Write, Views and Assignment, question 17 of the pandas sample
import pandas as pd
df = pd.DataFrame({'a': [1, 1, 2]})
resultat = df.drop_duplicates(inplace=True)
print(resultat, df['a'].tolist())What does this print?
Show the answer and why each option is right or wrong
Answer, A. None [1, 2]
- A. None [1, 2]
- Correct. drop_duplicates with inplace=True removes the repeated row directly from df and returns None, so resultat is None and df['a'] now reads [1, 2].
- B. None [1, 1, 2]
- Assumes the inplace call returns None correctly but the duplicate row was never actually removed from df.
- C. a\n0 1\n2 2 [1, 2]
- Assumes resultat holds the whole deduplicated DataFrame rather than None.
- D. [1, 2] [1, 2]
- Assumes resultat holds the deduplicated column as a list instead of None.
drop_duplicates with inplace=True follows the same convention as the other inplace methods here, mutate and return None. The duplicate is genuinely gone from df, the empty return value only reflects the call itself, not the state of df.
The answer above is what pandas 3.0.5 printed when the snippet was run, not what someone expected it to do.
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