CODEWITHSUNDEEP
regexstringpython-3.xnumbers
user2448416
user2448416

Reputation: 119

Extract multi-digit numbers from a string in python 3

I am doing the algorithm challenges from HackerRank and one of the problems needs me to accept input in the form of strings of numbers formatted as follows:

3 4
12 14 16
1 2
3 4
5 6

Now, I know how to iterate through the lines and assign them where they need to go, but my issue is with the second line. The others are two two digit numbers so I've been extracting them by just referencing their index in the string. For example, the first line of numbers would be collected with string[0] and string[-1].

The second line, however is of indeterminate length, and may include numbers shorter or longer than three digits. How would I pull those out and assign them to variables? I'm sure there is probably a way to do it with RegEx, but I don't know how to assign multiple matches in one string to multiple variables.

Upvotes: 3

Views: 4552

Answers (4)

vks
vks

Reputation: 67988

  import re
  print(re.findall(r"(\d+)",x))

"x" being your line.This will return a list with all the number.

Upvotes: 3

dawg
dawg

Reputation: 104032

Given:

>>> txt='''\
... 3 4
... 12 14 16
... 1 2
... 3 4
... 5 6'''

If the lines have meaning, you can do:

>>> [map(int, line.split()) for line in txt.splitlines()]
[[3, 4], [12, 14, 16], [1, 2], [3, 4], [5, 6]]

If the lines have no meaning, you just want all the digits, you can do:

>>> map(int, txt.split())
[3, 4, 12, 14, 16, 1, 2, 3, 4, 5, 6]

If your source text has the possibility of strings that will not convert to integers:

>>> txt='''\
... 3 4
... 12 14 16
... 1 2
... 3 4
... 5 6
... text that won't be integers
... 99 100 101'''

You can use a conversion function:

>>> def conv(s):
...    try:
...       return int(s)
...    except ValueError:
...       return s
... 
>>> [[conv(s) for s in line.split()] for line in txt.splitlines()]
[[3, 4], [12, 14, 16], [1, 2], [3, 4], [5, 6], ['text', 'that', "won't", 'be', 'integers'], [99, 100, 101]]

Or filter out the things that are not digits:

>>> map(int, filter(lambda s: s.isdigit(), txt.split()))
[3, 4, 12, 14, 16, 1, 2, 3, 4, 5, 6, 99, 100, 101]

Upvotes: 0

Falko
Falko

Reputation: 17897

So if s is your string,

map(int, s.split())

yields a list of integers:

[3, 4, 12, 14, 16, 1, 2, 3, 4, 5, 6]

That's basically what skamazin suggested.

Upvotes: 0

Avinash Raj
Avinash Raj

Reputation: 174796

You mean this?

>>> import re
>>> s = """3 4
... 12 14 16
... 1 2
... 3 4
... 5 6"""
>>> m = re.findall(r'\b\d+\b', s, re.M)
>>> m
['3', '4', '12', '14', '16', '1', '2', '3', '4', '5', '6']

Just pickup each value in the final list and assign it to variables.

Upvotes: 0

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