I have this list
item = [
[1, 2, 'W', 4, 5],
[16, 17, 'W', 19, 20],
[],
[],
[],
['1', '', 'D', '3120', '3456']
]
I need to get position 2 of each element where we have values.
I'm trying
v_sal = [x for x, sal in enumerate(item) if sal]
x = [i for i in item if i]
for i in range(0,len(x)):
for pos, val in enumerate(x[i]):
v2=pos[2]
I need to assign position 2 of each array in a variable but I have this error
TypeError: 'int' object is not subscriptable
I assume this is your expected output for "position 2" in the meaning of the second position which would be index 1
for a list
in Python:
[2, 17, '']
I absolutely don't see why you need enumerate()
here.
Here is the solution for this.
result = []
for element in item:
try:
result.append(element[1])
except IndexError:
pass
print(result)
You don't have to explicit check if there are values in the element or not. Just catch the exception.
You may utilize itertools
library, or more-itertools
, which is extremely useful when you work with an iterable object.
from itertools import islice
item = [
[1, 2, 'W', 4, 5],
[16, 17, 'W', 19, 20],
[],
[],
[],
['1', '', 'D', '3120', '3456']
]
# https://more-itertools.readthedocs.io/en/stable/_modules/more_itertools/recipes.html#nth
def nth(iterable, n, default=None):
"""Returns the nth item or a default value.
>>> l = range(10)
>>> nth(l, 3)
3
>>> nth(l, 20, "zebra")
'zebra'
"""
return next(islice(iterable, n, None), default)
if __name__ == "__main__":
f1 = [nth(l, 1) for l in item]
f2 = [snds for l in item if (snds:=nth(l, 1)) is not None] # Walrus operator is available > 3.8
print(f1)
# [2, 17, None, None, None, '']
print(f2)
# [2, 17, '']
See, https://more-itertools.readthedocs.io/en/stable/_modules/more_itertools/recipes.html#nth
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