Pandas: Trouble Setting a Slice to a Value

Asked Jan 26 '18 at 17:27

Active Jan 26 '18 at 17:35

Viewed 36 times

I'm trying to use boolean indexing to set the rows with a Title not in ["Mr", "Miss", "Mrs", "Master"] to Rare. Here's my attempt:

combined_df[(~combined_df.Title.isin(["Mr", "Miss", "Mrs", "Master"]))].Title = "Rare"

When I do pd.value_counts(combined_df.Title), I get:

Mr              757
Miss            260
Mrs             197
Master           61
Dr                8
Rev               8
Col               4
Major             2
Mlle              2
Ms                2
Jonkheer          1
the Countess      1
Capt              1
Dona              1
Don               1
Lady              1
Mme               1
Sir               1
Name: Title, dtype: int64

So the attempted changes don't take hold.

Any idea why / how to fix this?

asked Jan 26 '18 at 17:27

anon_swe

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`combined_df.loc[~combined_df.Title.isin(["Mr", "Miss", "Mrs", "Master"]), 'Title'] = 'Rare'` – ayhan Jan 26 '18 at 17:34
Are you sure this is done inplace? – roganjosh Jan 26 '18 at 17:34
You can use the below code: `value = df['Title'].isin(['Mr','Mrs','Miss','Master']) column_name = 'B' df.loc[value, column_name] = "Rare"` – user15051990 Jan 26 '18 at 17:38

Pandas: Trouble Setting a Slice to a Value

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