Sun, 28 May 2023

How To Read a CSV File in Python?

19 May 2023, 20:24 GMT+10

A Comma Separated Values (CSV) file is one of the most commonly used ways of exchanging and storing tabular data. It stores data in plain text and is based on a table of rows and columns, where each row is separated by a comma and each column by a delimiter. CSV files are easy to create and open with most text editors or spreadsheet programs such as Microsoft Excel, Google Sheets, or IBM Lotus 1-2-3.

If you want to learn how to read CSV files in Python, then you've come to the right place. Python provides a CSV module that makes working with CSV files easier. With this module, you can read and write CSV files easily. It allows you to read the contents of a CSV file into memory and make adjustments as needed.

Here are a few ways to read CSV files in Python.

Reading CSV Files in Python Using .redlines()

To read a CSV file in Python using the .readlines() method, you can follow these steps:

  • Open the CSV file using the open() function.
  • Use the .readlines() method to read the contents of the file and store them as a list of lines.
  • Iterate over the lines and process them as needed.

Here's an example:

In the above code, data.csv is the name of the CSV file you want to read. The open() function is used to open the file, and the 'r' argument specifies that it should be opened in read mode. The .readlines() method reads the contents of the file and returns a list of lines.

Each line is processed individually. The strip() method removes any leading or trailing whitespace, and the .split(',') method splits the line into a list of values using the comma as the delimiter. You can replace ',' with the appropriate delimiter used in your CSV file.

Once you have the values, you can access them using their indices, similar to accessing elements in a list. If the CSV file has a header row, you can extract the header line from the lines list and use it to access values by column name, just like in the commented alternative code.

Remember to replace 'column_name' with the actual name of the column you want to access in the CSV file.

Read a CSV File Using csv.DictReader

To read a CSV file in Python using csv.DictReader, you can follow these steps:

  • Import the csv module.
  • Open the CSV file using the open() function.
  • Create a csv.DictReader object, passing the opened file as the argument.
  • Iterate over the rows of the CSV file using a for loop.
  • Access the values by column names using the keys of the dictionary.

Here's an example:


CSV files are a great way to store tabular data in plain text format. The Python CSV library provides numerous functions to help you read and write csv files. With the help of these functions, you can easily work with csv files in Python.

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