使用 indeces 迭代元组列表理解

Question

I'm trying to iterate over a list comprehension tuple using indeces to reference each tuple and its associated length and then printing out each element within the tuple list, but python is not accepting this. I'm a comp sci major but about 10 years ago and we learned off C++ and Java, so am still new to python:

q = 0    
productResourcePairs = [(x, y) for x in [1,2,3] for y in [3,1,4]]
    for p in productResourcePairs:
        for i in range(len(productResourcePairs(p))):
             print(productResourcePairs[q][i])
        q = q + 1

I'm simply trying to get the length of each tuple and then print out using [][] its correspdoning value and then moving onto the next tuple.

Python throws the following error:

Traceback (most recent call last): for i in range(len(productResourcePairs(p))): TypeError: 'list' object is not callable

It's working now and will close this out just noting the fixes and the bottom calls yield the same result with respect to the tuple:

for p in productResourcePairs:

    for i in range(len(p)):
        print(p[i])
        print(productResourcePairs[q][i])
    q = q + 1

Answer 1

() are the call operator, so productResourcePairs(p) is trying to call your list - which makes no sense since lists are not callable. productResourcePairs[p] is trying to get the element at index p of your list - but here p is a tuple , not an int , and you obviously cannot index a list with a tuple.

Now I'm not really sure what you're trying to do, but if the goal is to print each element of each tuple in your list, then you're making things much more complicated than they have to be:

productResourcePairs = [(x, y) for x in [1,2,3] for y in [3,1,4]]
for p in productResourcePairs:
    for item in p:
        print(item)

I kindly suggest you do the full official Python tutorial, it covers all those points.

EDIT :

if you absolutely insist on using indexed access, even though it's both unpythonic, uselessly complicated and much less efficient (for the above use case), you can of course still do so:

productResourcePairs = [(x, y) for x in [1,2,3] for y in [3,1,4]]
for p in productResourcePairs:
    plen = len(p)
    for i in range(plen):
        print(item[i])

or if you want to do even worse:

productResourcePairs = [(x, y) for x in [1,2,3] for y in [3,1,4]]
llen = len(productResourcePairs) 
for i in range(llen):
    plen = len(productResourcePairs[i])
    for j in range(plen):
        print(productResourcePairs[i][j])

Note that any experimented Python user would immediatly replace this code with my first snippet if they were to find this in the code base they're working on.

Answer 2

This is the correct code:

for p in productResourcePairs:

    for i in range(len(p)):
        print(p[i])
        print(productResourcePairs[q][i])
    q = q + 1