How to Open a CSV File in Python?

This article will show you how to open a CSV file in Python using the built-in csv module.

Checkout this video:

Introduction

A CSV file, which is a “comma separated values” file, allows you to save your data in a table structured format, which is useful when you need to manage a large database. Python provides the csv module for reading and writing csv files. You can also use the with statement to open a file…

What is a CSV file?

CSV files are comma-separated values files, they store data in plain text format where each line is a data record consisting of one or more fields, with each field separated by a comma. When you open a CSV file in Python, you can read all the data in it as a list of lists, where each inner list represents a row of data.

The structure of a CSV file

A CSV file (Comma Separated Values file) is a type of plain text file that uses specific structuring to arrange tabular data. Because it’s a plain text file, it can contain only actual text data—in other words, printable ASCII or Unicode characters.

Each line in a CSV file is a data record. Each record consists of one or more fields, separated by commas. For example, let’s say we have a CSV file with the following contents:

name,age,city,country
John Smith,25,New York,USA
Jane Doe,30,London,England
Joe Bloggs,40,Paris,France
This CSV file has four records (lines) and four fields (columns). The first line contains the field names; the other lines contain data records.

How to open a CSV file in Python

CSV (comma separated values) files are a common format used when importing or exporting data. Python has built-in functions for reading and writing CSV files, but in this article we will focus on the former.

In order to open a CSV file in Python, we first need to import the CSV module. We can do this by typing the following into our terminal:

import csv

Once the module is imported, we can use the function csv.reader() to create a reader object. This object will allow us to read in and manipulate our data. The syntax for this function is as follows:

csvfile = open(‘filename.csv’, ‘r’)
reader = csv.reader(csvfile)
for row in reader:
print row
We pass our file handle into the csv.reader() function and store the resulting reader object in a variable called reader. We can then iterate over this object using a for loop to print out each row of data as a list.

Reading data from a CSV file

A CSV (comma-separated values) file is a text file that stores tabular data. It can be opened in any text editor, but it is best viewed and edited using a spreadsheet program such as Microsoft Excel, Google Sheets, or LibreOffice Calc.

CSV files are commonly used to store data from databases or spreadsheets. They are also used to transfer data from one application to another. For example, you might export the contacts from your email program as a CSV file, and then import them into your address book.

CSV files use commas to separate values (or columns of data). Each row of data must have the same number of values. If you have a CSV file with headers (column titles), the headers will be used to create keys in the dictionary.

Writing data to a CSV file

Python’s Built-in csv module makes it easy to read and write CSV files. It handles all the details of opening and closing files, reading and writing data, and parsing and formatting CSV data.

The first step is to import the built-in csv module. This module provides a number of functions that make working with CSV files much easier:

import csv

Once imported, you can create a reader object using the reader() function. This function takes two arguments:

csvfile: the file object you want to read from (typically open in ‘r’ mode)
dialect: optional dialect parameter which specifies how the CSV file is formatted.If omitted, the default dialect ‘excel’ is used.
import csv

with open(‘file.csv’, ‘r’) as csvfile:
reader = csv.reader(csvfile, dialect=’excel’)

Closing a CSV file

A CSV file is a typed of comma-separated values file that you can use to store data. It is a text file where each line contains a data record. Each record consists of one or more fields, separated by commas.

CSV files are commonly used to store tabular data, such as database table contents, but they can also be used for other purposes such as storing lists of books or movies.

To close a CSV file in Python, you need to use the close() method on the file object. This will close the file and save any changes you have made.

CSV file errors

CSV files are very easy to work with programmatically. However, they can sometimes be hard to work with if you are not used to their format. In this article, we will show you how to open a CSV file in Python using the csv module.

The first thing you need to do is open the CSV file in text mode. You can do this by using the open() function. The open() function takes two arguments: the name of the file and the mode in which you want to open the file:

csvfile = open(‘filename.csv’, ‘r’)
The first argument is the name of the CSV file. The second argument is the mode in which you want to open the file. The ‘r’ mode stands for read-only mode. In this mode, you can only read from the CSV file; you cannot write to it or modify it in any way.

Once you have opened the CSV file, you can use the reader() function fromDebuggingPython 2’s csv module to read from it. The reader() function accepts a delimiter as an optional argument. A delimiter is a character that is used to separate values in a CSV file (e,g., a comma). By default, reader() uses a comma as a delimiter:

reader = csv.reader(csvfile)
You can now use Python’s for loop construct to iterate through all of the rows in the CSV file:

for row in reader:
print row

Conclusion

So this is how you can open a CSV file in Python. You first have to import thecsv module and then create a reader object. You can then loop over the rows in the reader object and process them as you like.

Scroll to Top