Selecting multiple columns in Pandas - Cheat Sheet & Quick Revision

Recall & Review

beginner

How do you select multiple columns from a pandas DataFrame?

You select multiple columns by passing a list of column names inside double square brackets, like df[["col1", "col2"]].

beginner

What type of object is returned when selecting multiple columns from a DataFrame?

Selecting multiple columns returns a new DataFrame containing only those columns.

intermediate

What happens if you select a single column using double square brackets, like df[["col1"]]?

You get a DataFrame with one column, not a Series. Single square brackets return a Series, double brackets return a DataFrame.

intermediate

Can you select columns by position using the same method as selecting by name?

No, selecting by position uses df.iloc, while selecting by name uses df[[...]].

beginner

Why might you want to select multiple columns from a DataFrame?

To focus analysis on specific data, reduce memory use, or prepare data for visualization or modeling.

Which syntax correctly selects columns 'A' and 'B' from DataFrame df?

A df[['A', 'B']]

B df['A', 'B']

C df.loc['A', 'B']

D df.iloc['A', 'B']

Use double square brackets with a list of column names to select multiple columns.

What type of object is returned by df[['A', 'B']]?

A DataFrame

B Series

C List

D Dictionary

Selecting multiple columns returns a DataFrame.

How do you select columns by position instead of name?

A df[['0', '1']]

B df.iloc[:, [0, 1]]

C df.select([0, 1])

D df.loc[0, 1]

Use df.iloc with column positions inside a list to select columns by position.

What does df[['A']] return?

A An error

B A Series

C A list

D A DataFrame with one column

Double brackets return a DataFrame, even if selecting one column.

Why is selecting multiple columns useful?

A To change data types

B To delete data

C To focus on specific data for analysis

D To rename columns

Selecting columns helps focus on relevant data for analysis or visualization.

Explain how to select multiple columns from a pandas DataFrame and what the result looks like.

Think about how you pick multiple items from a list.

Describe the difference between selecting a single column with single brackets and double brackets in pandas.

Consider the type of object returned.