python map vs list comprehsnion

Question

I am trying to return the min and max of a string of numbers, ie. ("1 2 3 4 5 6")

The code that I came up with is as follows

def high_and_low(numbers):
    numbers = numbers.split(' ')
    map(int, numbers)
    return str(max(numbers)) + ' ' + str(min(numbers))

This code does not work for the following example:

print(high_and_low("4 5 29 54 4 0 -214 542 -64 1 -3 6 -6"))
6 -214

However, a similar function crafted as:

def min_and_max(numbers):
    nn = [int(s) for s in numbers.split(' ')]
    return "%i %i" % (max(nn),min(nn))

Returns the correct answer

print(min_and_max("4 5 29 54 4 0 -214 542 -64 1 -3 6 -6"))
542 -214

Shouldn't

map(int, numbers)

be the same as

[int(number) for number in numbers]

Why do the two functions not return the same values?

Answer 1

In your high_and_low method, map(int, numbers) is not being assigned to a value.

def high_and_low(numbers):
    numbers = numbers.split(' ')
    numbers = map(int, numbers)
    return str(max(numbers)) + ' ' + str(min(numbers))

Also, map returns an iterator in Python 3.x. Your min(numbers) will error because max will exhaust the iterator and throw a ValueError due to an empty sequence. So you need to convert it to a list

def high_and_low(numbers):
    numbers = numbers.split(' ')
    numbers = list(map(int, numbers))
    return str(max(numbers)) + ' ' + str(min(numbers))