How Do I Change DataFrame Data Type in Python?


Larry Thompson

In this tutorial, we will learn how to change the data type of a DataFrame in Python. The pandas library provides a convenient way to manipulate and analyze data using DataFrame objects. Sometimes, we may need to modify the data type of one or more columns in a DataFrame to perform specific operations or calculations.

Table of Contents

  1. Introduction
  2. Understanding Data Types
  3. Converting Data Types
  4. Summary


DataFrames are two-dimensional data structures provided by the pandas library. They consist of rows and columns, similar to tables in a relational database. Each column in a DataFrame has a specific data type, such as integers, floats, strings, or dates.

However, sometimes the default data type assigned by pandas may not be suitable for our analysis or calculations. Therefore, it becomes necessary to change the data type to perform certain operations.

Understanding Data Types

Before we dive into changing the data types of a DataFrame, let’s take a quick look at some common data types available in pandas:

  • Numeric Data Types: These include integers and floats representing numerical values. Examples include int64 (64-bit integer) and float64 (64-bit floating-point number).
  • String Data Types: These represent text or string values.

    The primary string data type in pandas is object.

  • Datetime Data Types: These represent dates and times. The datetime64 data type is used to store date and time information.
  • Categorical Data Types: These represent categorical or discrete variables. Categorical data types can be useful when working with nominal or ordinal data.

Converting Data Types

Now that we have a basic understanding of the different data types, let’s explore how to change the data type of a DataFrame in Python using pandas.

Converting a Single Column

To change the data type of a single column, we can use the astype() method provided by pandas. This method allows us to specify the desired data type for the column.

Let’s assume we have a DataFrame called df, and we want to convert the ‘age’ column from integer to float:

import pandas as pd

# Create a DataFrame
df = pd.DataFrame({'name': ['John', 'Alice', 'Sam'],
                   'age': [25, 30, 35],
                   'city': ['New York', 'London', 'Paris']})

# Convert the 'age' column from int64 to float64
df['age'] = df['age'].astype(float)

In this example, we use the astype() method to convert the ‘age’ column from int64 to float64. The modified DataFrame will now have the desired data type for the specified column.

Converting Multiple Columns

When we need to change the data type of multiple columns in a DataFrame, we can use the astype() method with a dictionary.

Let’s say we want to convert the ‘age’ column to float and the ‘city’ column to string. Here’s how we can achieve that:

# Define a dictionary with column names and desired data types
convert_dict = {‘age’: float,
‘city’: str}

# Convert the specified columns to their respective data types
df = df.astype(convert_dict)

In this example, we define a dictionary called convert_dict that maps column names to their desired data types. We then pass this dictionary to the astype() method, which converts the specified columns in the DataFrame.


In this tutorial, we learned how to change the data type of a DataFrame in Python using pandas. We explored different data types available in pandas and saw how to convert single or multiple columns to specific data types.

Remember that changing the data type of a column may result in loss of information or precision. It’s essential to consider any potential implications before modifying the data type. Additionally, always ensure that your data is clean and consistent before performing any conversions.

Now you have the knowledge and tools to manipulate DataFrame data types efficiently. Happy coding!

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