How To Convert String To Float In Python CSV File

In this tutorial, you’ll learn how to convert a string to a float in a Python CSV (Comma Separated Values) file.

This is a common task in data processing where you need to perform mathematical operations on numerical values stored as strings. We’ll walk you through the process step by step, providing code examples for better understanding.

Step 1: Import the required libraries

The first step is to import the csv module, which is a part of the Python standard library. This module provides functionality to read from and write to CSV files.

1
import csv

Step 2: Open and read the CSV file

To open and read a CSV file, you can use the open() function followed by the csv.reader() function. The open() function accepts two arguments – the name of the file and the mode in which the file should be opened (‘r’ for read mode in this case). Here’s an example:

1
2
3
file = 'example.csv'
with open(file, 'r') as csvfile:
    csvreader = csv.reader(csvfile)

Suppose your example.csv file looks like this:

value1,value2
"3.14","7.88"
"8.42","1.44"

Step 3: Iterate through the rows and convert string to float

Now that you have opened the file and created a csv.reader object, you can iterate through the rows and convert the strings to float. We’ll use the float() function to achieve this.

1
2
3
4
5
6
7
8
9
10
11
with open(file, 'r') as csvfile:
    csvreader = csv.reader(csvfile)
 
    # Skip the header row
    next(csvreader)
 
    # Iterate through the rows
    for row in csvreader:
        value1_float = float(row[0])
        value2_float = float(row[1])
        print(value1_float, value2_float)

At this point, the strings have been successfully converted to floats.

Output

3.14 7.88
8.42 1.44

Full Code

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
import csv
 
file = 'example.csv'
 
with open(file, 'r') as csvfile:
    csvreader = csv.reader(csvfile)
 
    # Skip the header row
    next(csvreader)
 
    # Iterate through the rows
    for row in csvreader:
        value1_float = float(row[0])
        value2_float = float(row[1])
        print(value1_float, value2_float)

Conclusion

In this tutorial, you learned how to convert a string to a float in a Python CSV file. We used the csv module to read the file, and the float() function to convert the string values to float. This is a useful skill, especially when working with datasets that require numerical operations.