How do I convert string to integer in python?

Question

I have a python program for sorting out class scores. My Class1 text file looks like this:

Elizabeth, 2, 7, 3

Anna, 9, 6, 4

Jenny, 8, 1, 5

Victoria, 1, 4, 7

This is my code so far:

file=open("Class1.txt","r")

studentscores= []

for row in file:

    studentscores.append(row.strip())

studentscores2=[]

for item in studentscores:

    studentscores2.append(item.split(","))

I'm struggling how to how to convert the string into integers so that I can sort the numbers? I would appreciate some help.

...with [`int`](https://docs.python.org/2/library/functions.html#int)? — jonrsharpe, Apr 29 '15 at 19:36
possible duplicate of [Parse String to Float or Int](http://stackoverflow.com/questions/379906/parse-string-to-float-or-int) — Rod, Apr 29 '15 at 19:37

Adem Öztaş · Answer 1 · 2015-04-29T20:15:14.250

2

s = '''Elizabeth, 2, 7, 3
   ...: Anna, 9, 6, 4
   ...: Jenny, 8, 1, 5
   ...: Victoria, 1, 4, 7'''
[int(word) for line in s.splitlines() for word in line.split(',') if word.strip().isdigit()]
[2, 7, 3, 9, 6, 4, 8, 1, 5, 1, 4, 7]

edited Apr 29 '15 at 20:15

answered Apr 29 '15 at 19:46

Adem Öztaş

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I dislike this approach, since it can't handle any score over one digit long. I would split by commas instead, treat the first element as a name, and the rest as scores. – Shashank Apr 29 '15 at 19:54
Actually I just realized my comment made no sense, since split produces a list. A better way would be: `[[int(word) for word in (word.strip() for word in line.split(',')) if word.isdigit()] for line in s.splitlines()]` This produces a list of lists of the form: `[[2, 7, 3], [9, 6, 4], [8, 1, 5], [1, 4, 7]]` But your approach is fine as well :) Upvoting. – Shashank Apr 29 '15 at 20:14
Or, more simply: `[[int(word) for word in line.split(',') if word.strip().isdigit()] for line in s.splitlines()]` This allows each student's scores to be handled separately in its own list. – Shashank Apr 29 '15 at 20:18

ZdaR · Answer 2 · 2015-04-29T19:44:59.103

your code can be effectively rewritten as :

scorecard = []
with open("Class1.txt","r") as marks_file:
    for scores in marks_file.readlines():
        scorecard.append(map(int, scores.split(", ")[1:]))

The map function here is used to implement a function over a given list, and for converting a valid string to an integer we use int("100") where "100" is a string which is converted to an integer, So we use the map function to do the same over the given set of strings.

letsc · Answer 3 · 2015-04-29T19:40:05.853

-1

Look into the map() built in function in python

Assuming studentscores is the name of the list, just do

map(int,studentscores)

edited Apr 29 '15 at 19:40

answered Apr 29 '15 at 19:37

letsc

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The OP is asking for converting strings to integers. – ZdaR Apr 29 '15 at 19:39

How do I convert string to integer in python?

3 Answers3