Extract data csv file and write in another file

[alexgrand]

I have to write a Python application to read a CSV input file (appsUsage.csv) and generate an output file counting the frequency of the apps usage per user. The first column of the input file contains user id (user_id) and the second column contains the name of the app (app_name). From appsUsage.csv, I have to count the frequency of apps usage on individual user basis to generate app_Rank, and transform to a new data set named appsIndividualUsage.csv with the following columns: user_id; app_name; app_Rank.
For example if appsUsage.csv has following events

a facebook a facebook a linkedin b google b yahoo b yahoo

Then appsIndividualUsage.csv would be:

a facebook 2; a linkedin 1; b google 1; b yahoo 2;

Here is my code that I am struggling with :

>>>import csv with open(‘C:\\Users\\anne\\Desktop\\appsUsage.csv’, mode='r') as f_in, open(‘C:\\Users\\anne\\Desktop\\appsIndividualUsage.csv’, mode='w', newline='') as f_out: 
f_reader = csv.reader(f_in, dialect=csv.excel_tab) 
f_writer = csv.writer(f_out, dialect=csv.excel_tab) 
for line in reader: 
if line is equal then write it in writer and add a row of frequency

i totally don't know how to write the last line of my code


If someone can help 


Thank you