[Tutor] how to use int and split() simultaneously

[शंतनू]

On 08-Dec-2011, at 7:13 PM, Dario Lopez-Kästen wrote:

> oh, yes,  no top posting. See below.
> 
> On Thu, Dec 8, 2011 at 1:33 PM, surya k <suryak at live.com> wrote:
> 
> This is something I am trying to do..
> Say, we are entering a string "1 2 3 4 5".so, I want to assign the numbers directly as numbers. how can I do it?
> I could put that numbers as string but not as number..
> strNum = raw_input('enter:').split()
> I can convert the list into numbers by doing this...
> for i in range(len(strNum)):   strNum[i] = int(strNum[i]).
> but I feel, its a long process. How can I do it in the shortest possible way??
> 
> Using a list comprehension is one example of a compact way of doing it:
> 
> strNum = raw_input("enter numbers, separated by space: ").split()
> strNum = [int(x) for x in strNum]
>  
> You would have to assume that the entire string consists of tokens that can be type cast into integers. If not you get an error:
> 
> >>> strNum = raw_input("enter numbers, separated by space: ").split()
> enter numbers, separated by space: 1 2 3 4 5 66 asd
> >>> strNum = [int(x) for x in strNum]
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> ValueError: invalid literal for int(): asd
> 
> In that case a for loop with a try-except would better:
> 
> strNum = raw_input("enter numbers, separated by space: ").split()
> num_list = []
> 
> for token in strNum:
>     try:
>         num_list.append(int(token))
>     except ValueError:
>         # Do nothing, fetch the next token
>         continue
> 
> print repr(num_list)
> 
> This code gives this result:
> 
> enter numbers, separated by space: 1 2 3 4 5 66 
> [1, 2, 3, 4, 5, 66]
> 
> enter numbers, separated by space: 1 2 3 4 5 66 asd 77
> [1, 2, 3, 4, 5, 66, 77]
> 
> Strictly speaking the "continue" in the except clause is not necessary in this simple example.
> 
> Hope this helps!
> 
> /dario
> 

Using re module:

===
import re
strNum = raw_input("enter numbers, separated by space: ")
if re.search('[^\d ]', strNum):
    print('Invalid input')
else:
    data = [int(x) for x in strNum.split()]
    print(data)
===
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