Changing data types (astype) in Data Analysis Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the astype() method do in pandas?

The astype() method changes the data type of a pandas Series or DataFrame column to a specified type, like integer, float, or string.

beginner

How do you convert a column named 'age' in a DataFrame df to integers?

Use df['age'] = df['age'].astype(int) to convert the 'age' column to integer type.

beginner

Why might you want to change a column's data type in a DataFrame?

Changing data types helps with correct calculations, saving memory, or preparing data for analysis or visualization.

intermediate

What happens if you try to convert a column with text values to integers using astype(int)?

It will cause an error because text values cannot be directly converted to integers.

beginner

How can you convert a column to a string type using astype()?

Use df['column_name'] = df['column_name'].astype(str) to convert the column to string type.

What is the purpose of the astype() method in pandas?

A To change the data type of a column

B To sort the DataFrame

C To filter rows

D To rename columns

astype() changes the data type of a pandas Series or DataFrame column.

Which of these is a valid way to convert a column 'score' to float type?

A df['score'] = df['score'].astype(float)

B df.astype('score', float)

C astype(df['score'], float)

D df['score'].convert(float)

The correct syntax is df['score'] = df['score'].astype(float).

What error might occur if you try astype(int) on a column with text values?

A TypeError

B KeyError

C IndexError

D ValueError

Trying to convert text to int raises a ValueError.

Which data type can astype() NOT convert to directly?

A int

B complex nested object

C string

D float

astype() works with basic types like int, float, string, but not complex nested objects.

Why is it useful to convert a column to a numeric type?

A To sort alphabetically

B To change column names

C To perform mathematical operations

D To filter rows

Numeric types allow calculations and statistics on the data.

Explain how and why you would use the astype() method in pandas.

Think about preparing data for analysis or fixing data types.

What problems can arise if you try to convert text data to integers using astype(int)? How can you avoid them?

Consider what kind of data can be converted to numbers.