How to compare lines in data (.csv) file based on two values, then roll-up the data using Python? -

i have .csv file has 25 columns. in data, column 18 people_id, , column 19 donation date. have pre-sorted data using linux people id's appear together, sorted donation date in descending order.

here i'm not sure how proceed. need find lines have same people_id , donation date, sum various values, , output single line output. essentially, every line in file either different customer, or different donation date same customer. best use dictionary using people_id key? how syntactically?

i thinking this:

with open("file.csv") csv_file: row in csv.reader(csv_file, delimiter=','):     if row[18] in data_dict:         # something 

i'd recommend object-oriented approach.

import csv  class transaction:     def __init__(self, fields):         self.name, self.age, self.car, self.ident = fields # whatever fields have         # keep in mind these strings,         # may need process them before analysis     def calculation(self):         return self.age + self.id  transactions = {} open('csv_file.csv', newline='') f:     row in csv.reader(f):         bucket = tuple(row[18:20])         if bucket in transactions:             transactions[bucket].append(transaction(row))         else:             transactions[bucket] = [transaction(row)]  bucket in transactions:     print(bucket, sum(item.amount item in bucket.values())) 

this defines transaction class, instances of contain various fields come csv file. starts dictionary of transactions , looks through csv file, adding new transaction object new bucket (if given id , date haven't been seen before) or existing bucket (if given id , date have been seen before).

then goes through dictionary , performs calculation each bucket, printing bucket , result of calculation.