Working with CSV File in Python Class 12 Notes

CSV File in Python Class 12 Notes

What is CSV File

• A Comma Separated Values (CSV) file is a plain text file that contains the comma (,) separated data.
• These files are often used for exchanging data between different applications.
• CSV files are usually created by programs that handle huge amounts of data. They are used to export data from spreadsheets (ex:- excel file) and databases (Ex:- Oracle, MySQL). It can be used to import data into a spreadsheet or a database.

CSV File Structure
Name, DOB, City
Ram, 12-Jul-2001, Delhi
Mohan, 23-Jan-2005, Delhi

Python CSV Module

• CSV Module is available in Python Standard Library.
• The CSV module contains classes that are used to read and write tabular form of data into CSV format.
• To work with CSV Files, programmer have to import CSV Module.
  import csv

Methods of CSV Module :

1. writer( )
2. reader( )

Both the methods return an Object of writer or reader class. Writer Object again have two methods –

1. writerow( )
2. writerows( )

writer( ) Methods

This function returns a writer object which is used for converting the data given by the user into delimited strings on the file object.

writer( ) Object Methods –

• w_obj . writerow( <Sequence> ) : Write a Single Line
• w_obj . writerows ( <Nested Sequence> ) : Write Multiple Lines

writerow() Example:-

import csv
row=[‘Nikhil’, ‘CEO’, ‘2’, ‘9.0’]
f=open(“myfile.csv”, ‘w’)
w_obj = csv.writer(f)
w_obj.writerow(row)
f.close()

writerows() Example:

import csv
rows = [[‘Nikhil’,’CEO’,’2′,’9.0′],
[‘Sanchit’,’CEO’,’2′,’9.1′]]
f=open(“myfile.csv”,’w’)
w_obj = csv.writer(f)
w_obj.writerows(rows)
f.close()

reader( ) Methods

This function returns a reader object which will be used to iterate over lines of a given CSV file.

r_obj = csv.reader(csvfile_obj)

To access each row, we have to iterate over this Object.
for i in r_obj:
print(i)

import csv
f=open(“myfile.csv”,’r’)
r_obj = csv.reader(f)
for data in r_obj:
print(data)
f.close()