Convert String Column to Float Data Type in pandas DataFrame in Python (3 Examples)

This tutorial demonstrates how to change a string column to the float data type in a pandas DataFrame in the Python programming language.

Creation of Example Data

import pandas as pd                                  # Import pandas
df = pd.DataFrame({'A':['15', '2', '12', '9', '7'],  # Constructing a pandas DataFrame
                   'B':['10', '21', '4', '15', '25'],
                   'C':['35', '4', '51', '77', '8']})
print(df)
#     A   B   C
# 0  15  10  35
# 1   2  21   4
# 2  12   4  51
# 3   9  15  77
# 4   7  25   8
print(df.dtypes)                                     # Printing the data types of all columns
# A    object
# B    object
# C    object
# dtype: object

Example 1: Transforming One Column of a pandas DataFrame from String to Float

df1 = df.copy()                                      # Duplicate pandas DataFrame
df1['A'] = df1['A'].astype(float)                    # Converting string to float
print(df1.dtypes)                                    # Printing the data types of all columns
# A    float64
# B     object
# C     object
# dtype: object

Example 2: Transforming Multiple Columns of a pandas DataFrame from String to Float

df2 = df.copy()                                      # Duplicate pandas DataFrame
df2 = df2.astype({'A': float, 'C': float})           # Converting string to float
print(df2.dtypes)                                    # Printing the data types of all columns
# A    float64
# B     object
# C    float64
# dtype: object

Example 3: Transforming Each Column of a pandas DataFrame from String to Float

df3 = df.copy()                                      # Duplicate pandas DataFrame
df3 = df3.astype(float)                              # Converting string to float
print(df3.dtypes)                                    # Printing the data types of all columns
# A    float64
# B    float64
# C    float64
# dtype: object

Further Resources & Related Articles

You may find some related Python tutorials on topics such as groups and counting below:

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