list - chunking a large csv file by offset [0] in python -


i have csv file in format:

1,data,data2,data3..... 1,data,data2,data3..... 2,data,data2,data3..... 2,data,data2,data3..... 3,data,data2,data3..... 3,data,data2,data3..... 

i need chunk these strings offset[0] list such multiple lists with:

1,data,data2,data3..... 1,data,data2,data3..... 

and another:

2,data,data2,data3..... 2,data,data2,data3..... 

etc. have following code:

import csv filename = 'somefile.csv' open(filename) csv_file:     readcsv = csv.reader(csv_file, delimiter=',')     chunk1 = []     row in csv_file:         if row[0] '1':             print(row)         else:             break 

this gives first chunk need adapt chunks of same of set in lists.

assuming they're sorted first column, it:

import csv  itertools import groupby operator import itemgetter   filename = 'somefile.csv'  open(filename) csv_file:     csvreader = csv.reader(csv_file, delimiter=',')     chunks = [list(g) k, g in groupby(csvreader, itemgetter(0))] 

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