Python - Cast datatype of only a single column in a Pandas DataFrame

To cast only a single column, use the astype() method. Let us first create a DataFrame with 2 columns. One of them is a “float64” type and another “int64” −

dataFrame = pd.DataFrame(
   {
      "Reg_Price": [7000.5057, 1500, 5000, 8000, 9000.75768, 6000],
      "Units": [90, 120, 100, 150, 200, 130]
   }
)

Check the types −

dataFrame.dtypes

Let’s say we need to cast only a single column “Units” from int64 to int32. For that, use astype() −

dataFrame.astype({'Units': 'int32'}).dtypes

Example

Following is the code −

import pandas as pd

# Create DataFrame
dataFrame = pd.DataFrame(
   {
      "Reg_Price": [7000.5057, 1500, 5000, 8000, 9000.75768, 6000],
      "Units": [90, 120, 100, 150, 200, 130]
   }
)

print"DataFrame ...\n",dataFrame
print"\nDataFrame Types ...\n",dataFrame.dtypes
print"\nCast only a single column to int32..."

print"\nUpdated DataFrame Types ...\n",dataFrame.astype({'Units': 'int32'}).dtypes

Output

This will produce the following output −

DataFrame ...
   Reg_Price   Units
0 7000.50570     90
1 1500.00000    120
2 5000.00000    100
3 8000.00000    150
4 9000.75768    200
5 6000.00000    130

DataFrame Types ...
Reg_Price   float64
Units         int64
dtype: object

Cast only a single column to int32...

Updated DataFrame Types ...
Reg_Price   float64
Units         int32
dtype: object