Extract numbers from a list using Regex

You can do this with map :

lista = [u'1', u'2', u'3', u'4', u'7']

outraLista = list(map(int, lista))
print (outraLista) # [1, 2, 3, 4, 7]

Or use int to return an entire object:

lista = [u'1', u'2', u'3', u'4', u'7']

outraLista = [int(item) for item in lista if item.isdigit()]
print (outraLista) # [1, 2, 3, 4, 7]

If you want to continue using re.findall , pass the list as a < in> string with str :

import re

lista = [u'1', u'2', u'3', u'4', u'7']

outraLista = re.findall('\d+', str(lista))

for item in outraLista:
    print (item)

For lists in this way you can do this:

lista = [u'1', u'2', u'5', u'3', u'9', u'1']
result = [x for x in lista if re.match(r"\d+", x) ]

You do not need to use regular expressions for this, only if what you are looking for is in a large string, then the regex would look for a pattern and return those that would marry it.

But if you already have a list and want to extract only the numbers, just use a function that checks each element of the list by checking whether it is a digit or not.

Filter: Performs a function on each element of the list, and filters only those that return true.

>>> lista_qualquer = [u'1',u'2',u'3',u'4',u'7','teste','casa']
>>> e_um_numero = lambda numero : numero:isdigit()
>>> numeros = filter(e_um_numero,lista_qualquer)

And to convert each element of the list only with numbers to integers simply use the map that executes a function on each element of the list.

>>> numeros = map(int,numeros)
[1,2,3,4,7]