How to Filter a CSV File in Python

This tutorial will guide you on how to filter a CSV (Comma Separated Values) file using Python. CSV is a simple file format used to store tabular data, such as a spreadsheet or database.

Python provides several ways to download HTML content from web pages. We will be showing you how to extract and filter data from CSV files using Python’s built-in csv module and pandas library.

Step 1: Importing Necessary Libraries

Before we begin, you need to install and import the necessary Python libraries. Run the following code to install pandas.

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pip install pandas

Then import the necessary libraries using the code below:

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import csv
import pandas as pd

Step 2: Reading a CSV File

After importing the needed libraries, the next step is to read our CSV file.

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data = pd.read_csv("data.csv")

Step 3: Inspecting the CSV File

Now that we have our CSV file loaded, we can take a look at the data to determine what we might want to filter.

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print(data.head())

Step 4: Filtering a CSV File

After identifying the column of interest, apply the filter function to select the data you want. In this example, we will filter out rows where the Age is greater than 30.

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filtered_data = data[data['Age'] > 30]
print(filtered_data.head())

Before the conclusion, below is the full code for filtering a CSV file in Python.

Full Code

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import csv
import pandas as pd
 
# Read the CSV file
data = pd.read_csv("data.csv")
 
# Print the first five rows
print(data.head())
 
# Filter and print the first five rows where 'Age' is greater than 30
filtered_data = data[data['Age'] > 30]
print()
print(filtered_data.head())

Output:

      Name  Age       Location
0    Alice   28       New York
1      Bob   35    Los Angeles
2  Charlie   42        Chicago
3    David   25  San Francisco
4      Eve   31         Boston

      Name  Age     Location
1      Bob   35  Los Angeles
2  Charlie   42      Chicago
4      Eve   31       Boston
5    Frank   45        Miami

Conclusion

That’s it! You have now learned how to filter a CSV file in Python. This is a very useful skill when you are dealing with larger datasets and you are interested only in specific records.

Don’t forget to save your data to a new file if you want to keep these changes. Knowing how to filter a CSV file in Python can significantly speed up your data analysis process and allows you to focus on tasks that add value.