Is there a way to output the numbers only from a python list?

Question

Simple Question:

list_1 = [ \'asdada\', 1, 123131.131, \'blaa adaraerada\', 0.000001, 34.12451235265, \'stackoverflow is awesome\' ]

I want

Answer 1

List comprehensions.

list_2 = [num for num in list_1 if isinstance(num, (int,float))]

Answer 2

list_2 = [i for i in list_1 if isinstance(i, (int, float))]

Answer 3

I think the easiest way is:

[s for s in myList if s.isdigit()]

Hope it helps!

Answer 4

All solutions proposed work only if the numbers inside the list are already converted to the appropriate type (int, float).

I found myself with a list coming from the fetchall function of sqlite3. All elements there were formated as str, even if some of those elements were actually integers.

cur.execute('SELECT column1 FROM table1 WHERE column2 = ?', (some_condition, ))
list_of_tuples = cur.fetchall()

The equivalent from the question would be having something like:

list_1 = [ 'asdada', '1', '123131', 'blaa adaraerada', '0', '34', 'stackoverflow is awesome' ]

For such a case, in order to get a list with the integers only, this is the alternative I found:

list_of_numbers = []
for tup in list_of_tuples:
    try:
        list_of_numbers.append(int(tup[0]))
    except ValueError:
        pass

list_of_numbers will contain only all integers from the initial list.

Answer 5

for short of SilentGhost way

list_2 = [i for i in list_1 if isinstance(i, (int, float))] 

to

list_2 = [i for i in list_1 if not isinstance(i, str)]

Answer 6

filter(lambda n: isinstance(n, int), [1,2,"three"])