Selecting rows (loc, iloc) in Data Analysis Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does loc do when selecting rows in a DataFrame?

loc selects rows by their labels or index names. It includes the last label in slicing.

beginner

How does iloc differ from loc when selecting rows?

iloc selects rows by their integer position, starting at 0. It excludes the last index in slicing.

beginner

What will df.loc[2:4] return if the DataFrame index is [0, 1, 2, 3, 4, 5]?

Rows with index labels 2, 3, and 4 inclusive.

beginner

What will df.iloc[2:4] return if the DataFrame index is [0, 1, 2, 3, 4, 5]?

Rows at integer positions 2 and 3 (index labels 2 and 3), excluding position 4.

intermediate

Can loc select rows using boolean conditions?

Yes, loc can select rows by passing a boolean mask (True/False values) to filter rows.

Which method selects rows by integer position in a DataFrame?

A loc

B filter_rows

C select_rows

D iloc

iloc selects rows by integer position, starting at 0.

What does df.loc[1:3] include when selecting rows?

A Rows at integer positions 1 and 2 only

B Rows with index labels 1, 2, and 3

C Rows with index labels 1 and 2 only

D Rows at integer positions 1, 2, and 3

loc includes the last label in slicing, so rows 1, 2, and 3 are included.

If a DataFrame index is ['a', 'b', 'c', 'd'], what does df.iloc[1:3] select?

A Rows with labels 'c' and 'd'

B Rows with labels 'a' and 'b'

C Rows with labels 'b' and 'c'

D Rows with labels 'b', 'c', and 'd'

iloc selects by position 1 and 2, which correspond to labels 'b' and 'c'.

Which of these is true about loc slicing?

A It includes the last label in the slice

B It excludes the last label in the slice

C It only works with integer indexes

D It cannot use boolean masks

loc includes the last label when slicing rows.

How can you select rows where a column 'age' is greater than 30 using loc?

A df.loc[df['age'] > 30]

B df.iloc[df['age'] > 30]

C df.loc['age' > 30]

D df.iloc['age' > 30]

Use a boolean mask inside loc to filter rows by condition.

Explain the difference between loc and iloc when selecting rows in a DataFrame.

Think about how you pick rows by name versus by number.

Describe how to select rows based on a condition using loc.

Use True/False values to pick rows.