CODEWITHSUNDEEP
pythoncsv
RawLamb
RawLamb

Reputation: 117

Python - How to convert a CSV column with number data into integers

I'm using Python for a project and have data in a .txt file that is set out like this for example

Brazil.800000
United Kingdom.1200000
Zimbabwe.5000

The first 'column' is the country and the second 'column is numerical data. They're separated by a period. My task is to sort the data numerically. I've managed to make some progress using the code below from a tutorial video I found.

import csv
import operator

inputFileName = ("worldpop(2).txt")
infile = open(inputFileName, "r")

csv1 = csv.reader(infile, delimiter = ".")

sort = sorted(csv1, key = operator.itemgetter(1))

for eachline in sort:
    print(eachline)

However, while this sorts the data by the second column, it considers the numerical data as strings rather than integers. Which means the result turns out as:

United Kingdom.1200000
Zimbabwe.5000
Brazil.800000

I'm totally stuck on how to get this program to see the second column as actual integers. Can you guys help?

Thanks a lot.

Edit: To clarify, I'm not trying to change the actual file, but rather just print the data in a sorted fashion to IDLE.

Upvotes: 2

Views: 4340

Answers (2)

Kasravnd
Kasravnd

Reputation: 107287

You need to convert the number to int so you should change the key to :

key=lambda x:int(x[1])

Also as a more pythonic way use with* to open the files instead opening the file without closing! sorted function with a proper key that sort the rows based on int numbers :

>>> import csv
>>> from operator import itemgetter
>>> with open('infile.txt', 'r') as csvfile:
...     spamreader = csv.reader(csvfile, delimiter='.')
...     for row in sorted((i for i in spamreader),key=lambda x:int(x[1])):
            print row

result: 

['Zimbabwe', '5000']
['Brazil', '800000']
['United Kingdom', '1200000']

Also you can use reverse=True arg in sorted function to get a descending result :

['United Kingdom', '1200000']
['Brazil', '800000']
['Zimbabwe', '5000']

*the with statement will close the files after that process terminated!

Upvotes: 0

kdopen
kdopen

Reputation: 8215

Replace the key function in your sort statement with one which converts the values to integers

sort = sorted(csv1, key = lambda x: int(x[1]))

Upvotes: 4

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