Get column names from CSV using Python

CSV (Comma Separated Values) files store tabular data as plain text, with values separated by commas. They are widely used in data analysis, machine learning and statistical modeling. In Python, you can work with CSV files using built-in libraries like csv or higher-level libraries like pandas.

In this article, we will explore the following three methods to extract column names from a CSV file.

• Using Python's CSV library to read the CSV file line and line and printing the header as the names of the columns.
• Reading the CSV file as a dictionary using DictReader and then printing out the keys of the dictionary.
• Converting the CSV file to a data frame using the Pandas library of Python.

Below is the snapshot of the dataset we are going to use in this article for demonstration, you can download it from here.

Using the csv Library

This method reads the CSV file using the csv.reader and then prints the first row, which contains the column names.

import csv

with open('path_for_data.csv') as csv_file:
    csv_reader = csv.reader(csv_file, delimiter=',')
    header = next(csv_reader)

print("List of column names:", header)

Output:

List of column names : ['Column1', 'Column2', 'Column3']

Explanation:

• csv.reader reads the file line by line.
• next(csv_reader) retrieves the first row, which is assumed to be the header.

Using csv.DictReader

This method reads the CSV as a dictionary, allowing you to extract the keys (column names) directly.

Steps:

• Open the CSV file using DictReader.
• Convert this file into a list.
• Convert the first row of the list to the dictionary.
• Call the keys() method of the dictionary and convert it into a list.
• Display the list.

import csv
with open('data.csv') as csv_file:
    csv_reader = csv.DictReader(csv_file)
    header = list(next(csv_reader).keys())

print("List of column names:", header)

Output :

List of column names : ['Column1', 'Column2', 'Column3']

Explanation:

• csv.DictReader() reads each row as a dictionary (keys = column names).
• next(csv_reader) retrieves the first row.
• .keys() gives you the column headers.
• list(...) converts the dict_keys object to a list.

Using Pandas

Pandas makes it very simple by reading the CSV into a DataFrame and then accessing the .columns attribute.

import pandas as pd

df = pd.read_csv('path_to_data.csv')

header = list(df.columns)

print("List of column names:", header)

Output :

List of column names : ['Column1', 'Column2', 'Column3']

Explanation:

• pd.read_csv() loads the CSV file into a DataFrame.
• df.columns holds the column names, which we convert into a list.

Related articles:

• CSV (Comma Separated Values)
• Pandas
• Python