How to take multiple sets of inputs separated by space and carriage return in Python 3?

Question

So we are allowing a user to enter the number sets they want to enter. Each set of input will contain two integers separated by space. Then, the carriage return denotes the next set of inputs. For example,

Enter number of sets: 3
1 3
2 4
5 6

Next we input these in variables a,b, perform same operations, display 3 results:

4
3
1

It should first take all inputs and then show all respective outputs. We have the logic of processing 1 set of input, but how do we loop it so that we can accept input in this format?

sets = int(input("Enter number of sets: "))
inputs = []
for n in range(sets):
    inputs[n] = int(input().strip())

This crashes with list out of range error. We were thinking of creating a list of lists to hold the pair of values. Any easier solutions?

EDIT: What I'm looking for is a way to solve this problem. It doesn't have to be done via lists specifically. It is not a generic list out of range problem. I do understand what is going wrong, I just need another way to do it.

Python will not let you assign to a previously unassigned index -- use `append` — Two-Bit Alchemist, Sep 05 '16 at 03:26
Possible duplicate of [IndexError: list assignment index out of range](http://stackoverflow.com/questions/5653533/indexerror-list-assignment-index-out-of-range) — Two-Bit Alchemist, Sep 05 '16 at 03:29

Raymond Hettinger · Accepted Answer · 2016-09-05T03:47:34.523

The input() is returning a string like "1 3". Parse that string with something like, a, b = map(int, input().split()). Save the output by using list.append().

from pprint import pprint

inputs = []
results = []
sets = int(input("Enter number of sets: "))
for n in range(sets):
    s = input()
    a, b = map(int, s.split())
    result = a + b
    inputs.append([a, b])
    results.append(result)
pprint(inputs)
pprint(results)

A sample session looks like this:

Enter number of sets: 3
1 3
2 4
5 6
[[1, 3], [2, 4], [5, 6]]
[4, 6, 11]

The learning points are:

Use str.split() to convert a string like "1 3" into a list like ['1', '3']
Use map() with int() to convert ['1', '3'] to [1, 3]
Use variable unpacking to extract the two values
Use append() to grow the inputs and results lists

How to take multiple sets of inputs separated by space and carriage return in Python 3?

1 Answers1