Python: List to integers
I have read a file in and converted each line into a list. A sample of the list looks like:
['15', '2', '0'], ['63', '3', '445', '456' '0'], ['23', '4', '0']
i want to retrieve the first number from each list and convert it to and integer so when i carry out the type function i.e.
type(x)
<type 'int'> is returned
Also when i print x the integers are printed individually rather than joined. i.e. if i took the first 3 numbers from the list above the numbers are not printed as:
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To cast your ints:
my_ints = [int(l[0]) for l in your_list]
To print them out:
print "".join(map(str, my_ints))
If you want a list with the first number of each list, [int(L[0]) for L in lines]
(assuming the list of lists is called lines
); if you want the first two numbers of each list (it's hard to tell from your question), [int(s) for L in lines for s in L[:2]]
; and so forth.
If you don't want a list of such numbers, but just to do one iteration on them, you can use a generator expression, i.e.:
for number in (int(s) for L in lines for s in L[:2]):
...do something with number...
or an equivalent nested-loop approach such as:
for L in lines:
for s in L[:2]:
number = int(s)
...do something with number...
# Converts all items in all lists to integers.
ls = [map(int, x) for x in the_first_list]
Or if you just want the first two items:
ls = [map(int, x[:2]) for x in the_first_list]
In python 3.x you'd have to also wrap the map in a list constructor, like this
ls = [list(map(int, x[:2])) ...
If I understood your question correctly, it is [int x[0] for x in list_of_lists]
lines = [['15', '2', '0'], ['63', '3', '445', '456' '0'], ['23', '4', '0']]
first_values_as_ints = [int(line[0]) for line in lines]
for x in first_values_as_ints:
print x,
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