Process specific element in array python

Lets assume that you deal with a constant order of the data structure like the list you provided in your example.

If i understand well :

You got an input list of nested lists and some floats.

[ [ A, B, C, D ], somefloat, [A, B, C, D ] somefloat ]

And you try to get a list of nested lists which take the last element of the first nested list and combine it with the next float into a new nested list like so :

[ [D, somefloat], [D, somefloat] ]

One solution could be to use list comprehension, like so :

data=[[655.0, 48.77, 6.0, '1'], 0.0, [655.0, 48.77, 5.0, '1'], 1.0, [657.0, 49.25, 5.0, '4'], 2.2870067774276484, [657.0, 49.25, 1.0, '1'], 5.40651458890106, [657.0, 49.25, 1.0, '5'], 5.40651458890106]

newdata = [[data[i][-1], data[i +1]] for i in range(0, len(data), 2)]
print(newdata)

Output

[['1', 0.0], ['1', 1.0], ['4', 2.2870067774276484], ['1', 5.40651458890106], ['5', 5.40651458890106]]

Let's break it down :

for i in range(0, len(data), 2) 
# will iterate through the first list, the range method here (starts from 0 to the length of the input list) will return the current index as "i" with step of two, for each iteration.

[data[i][-1]
#will take the current item (which is a nested list) and extract from it the last element, feel free to change the -1 by any index of the element you desire (if you decide to finally go with the third element, so change the -1 -which mean the last element- by 2 -which is the third element


data[i +1]
# will take the next element (which is the float number)

[data[i][-1], data[i +1]
# will put them in a nested list (feel free to use tuple or dict if you want to output another kind of nested data structure)