str.contains() for pattern matching in Pandas - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the str.contains() method do in pandas?

The str.contains() method checks if each string in a pandas Series contains a specified pattern or substring. It returns a Series of True or False values.

beginner

How can you use str.contains() to find rows with a specific word in a DataFrame column?

You can use df['column'].str.contains('word') to get a boolean Series. Then use it to filter rows: df[df['column'].str.contains('word')].

beginner

What parameter do you use in str.contains() to ignore case when matching?

Use the parameter case=False to make the pattern matching ignore uppercase or lowercase differences.

intermediate

What happens if the data contains missing values (NaN) when using str.contains()?

By default, str.contains() returns NaN for missing values. You can use na=False to treat missing values as False.

intermediate

Can str.contains() use regular expressions for pattern matching?

Yes, by default str.contains() uses regular expressions. You can disable this by setting regex=False if you want to match exact substrings.

What does df['col'].str.contains('abc') return?

A The count of 'abc' in the column

B A filtered DataFrame with rows containing 'abc'

C A Series of True/False indicating if 'abc' is in each string

D The first string containing 'abc'

str.contains() returns a Series of True or False for each row, showing if the pattern is found.

How do you make str.contains() ignore case?

A Use <code>case=True</code>

B Use <code>case=False</code>

C Use <code>ignore_case=True</code>

D Use <code>ignore=True</code>

Setting case=False makes the search case-insensitive.

What parameter do you use to treat missing values as False in str.contains()?

A na=False

B na=True

C fillna=False

D missing=False

The na=False parameter treats NaN values as False in the result.

If you want to match the exact substring without regex, what do you do?

A Set <code>regex=False</code>

B Set <code>regex=True</code>

C Use <code>exact=True</code>

D Use <code>match=True</code>

Setting regex=False disables regex and matches the exact substring.

What type of object does str.contains() return?

A DataFrame

B String

C List

D Boolean Series

str.contains() returns a Series of boolean values (True/False).

Explain how to use str.contains() to filter rows in a DataFrame based on a pattern.

Think about how to get True/False for each row and then select rows.

Describe the role of the regex, case, and na parameters in str.contains().

These parameters customize how the pattern matching works.