Retrieving the initial item from a nested list structure

To perform indexing, you can try the following approaches:
1. Solution 1:
Here is a rough way to achieve it:
Ideally, you should extract the search into a function that accepts the lists and the keyword.
2. Solution 2:
A possible solution is to use list slices.
Here is how you can implement it:
3. Solution 3:
Another approach is to extract two slices, one with the first element and one with the last, and then concatenate them.
The first index equal to “i” is represented by [‘X’, ‘X’, ‘X’] and x[0].
4. Solution 2:
You can use a combination of functions to remove the single quote characters around the string elements when you print.
5. Solution 3:
Here is a single liner solution for this.

Solution 1:

You’re on the right track. When your nested list is only one layer deep, you can use a list comprehension and -1 indexing to access both the first and last elements, just like you were attempting to do.

a = [[sublist[0],sublist[-1]] for sublist in x]


>>> a
[[1, 3], [4, 6], [7, 9]]

Solution 2:

Let’s explore the utilization of list slices:

x = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
x = [l[::len(l)-1] for l in x]


[[1, 3], [4, 6], [7, 9]]

Solution 3:

x = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
>>> [a[:1] + a[-1:] for a in x]
[[1, 3], [4, 6], [7, 9]]

To avoid repetition, I take out two slices: one containing the first element and the other containing the last element. These slices are then concatenated. This method is effective even when the sublists have varying lengths.

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