如何创建两个值的序列？

Question

I have a list with different combinations, ie:

list1 = [(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]

I also have another list, in my case one looking like:

list2 = [1,1]

What I would like to do is to take the two values of list2 , put them together as (1,1) , and compare them with the elements in list1 , then returning the index. My current attempt is looking like this:

def return_index(comb):
    try:
         return comb_leaves.index(comb)
    except ValueError:
         print("no such value")

Unfortunately, it cant find it, because it's not a sequence. Anyone with any good idea of how to fix this?

Answer 1

You are confusing "sequence" with "tuple". Lists and tuples are both sequences. Informally, a sequence is anything that has a length and supports direct indexing in addition to being iterable. A range object is considered to be a sequence too for example.

To create a two element tuple from any other sequence, use the constructor:

test_element = tuple(list_2)

Answer 2

list3 = tuple(list2)
print(list3 in list1) #Check if it exists.

Answer 3

list1 = [(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]
list2 = [1,1]

tup2 = tuple(list2)

list1.append(tup2)
print('list1:',list1)

print('index:', list1.index(tup2))

will give this:

list1: [(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2), (1, 1)]
index: 4

Not sure if unconditionally adding tup2 is what you want.

Maybe you ask for the index, if the 2nd list is in list1:

list1 = [(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]list2 = [1,1]

tup2 = tuple(list2)
if tup2 in list1:
    print('index:', list1.index(tup2))
else:
    print('not found')

That gives:

index: 4

the index function returns the first element that matches.

Answer 4

Try this:

list1 = [(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]
list2 = [1, 1]

def return_index(comb):
    try:
        return list1.index(tuple(comb))
    except ValueError:
        print("Item not found")

print(return_index(list2)) # 4

With this line:

list1.index(tuple(list2))

Convert list2 into a tuple from a list . list1 's elements are tuples, so to make the comparison, list2 needs to be a tuple . tuple(list2) turns [1, 1] into (1, 1) (the same type as the elements of list1 ).