I have a list of lists which look like this:
[[[12, 15, 0], [13, 15, 25], [14, 15, 25], [16, 16, 66], [18, 15, 55]]]
What would be the best way to extract all elements occurring at index position 1. I know I can use a for loop like;
for i in list:
for j in i:
print j[2]
But is there a more "pythonic" (short /easy /less code/ efficient) way to do this?
You can use a list comprehension:
>>> lst = [[[12, 15, 0], [13, 15, 25], [14, 15, 25], [16, 16, 66], [18, 15, 55]]]
>>> [x[1] for x in lst[0]]
[15, 15, 15, 16, 15]
>>>
The above is equivalent to:
lst = [[[12, 15, 0], [13, 15, 25], [14, 15, 25], [16, 16, 66], [18, 15, 55]]]
final_list = []
for sub_list in lst[0]:
final_list.append(sub_list[1])
except that it is a lot more concise and also avoids all those calls to list.append (which means that it is more efficient).
use list comprehension:
[ x[1] for x in my_list[0] ]
this is more general if nested list is moree...
[ y[1] for x in my_list for y in x ]
