How to convert strings into integers in Python?

Question

I have a tuple of tuples from a MySQL query like this:

T1 = ((\'13\', \'17\', \'18\', \'21\', \'32\'),
      (\'07\', \'11\', \'13\', \'14\', \'28\'),
               


        

Answer 1

Yet another functional solution for Python 2:

from functools import partial

map(partial(map, int), T1)

Python 3 will be a little bit messy though:

list(map(list, map(partial(map, int), T1)))

we can fix this with a wrapper

def oldmap(f, iterable):
    return list(map(f, iterable))

oldmap(partial(oldmap, int), T1)

Answer 2

I would agree with everyones answers so far but the problem is is that if you do not have all integers they will crash.

If you wanted to exclude non-integers then

T1 = (('13', '17', '18', '21', '32'),
      ('07', '11', '13', '14', '28'),
      ('01', '05', '06', '08', '15', '16'))
new_list = list(list(int(a) for a in b) for b in T1 if a.isdigit())

This yields only actual digits. The reason I don't use direct list comprehensions is because list comprehension leaks their internal variables.

Answer 3

You can do this with a list comprehension:

T2 = [[int(column) for column in row] for row in T1]

The inner list comprehension ([int(column) for column in row]) builds a list of ints from a sequence of int-able objects, like decimal strings, in row. The outer list comprehension ([... for row in T1])) builds a list of the results of the inner list comprehension applied to each item in T1.

The code snippet will fail if any of the rows contain objects that can't be converted by int. You'll need a smarter function if you want to process rows containing non-decimal strings.

If you know the structure of the rows, you can replace the inner list comprehension with a call to a function of the row. Eg.

T2 = [parse_a_row_of_T1(row) for row in T1]