Unpacking a list of list of list

Question

The current input I use in my program is a list of list of coordinates:

data = [["D_02", "10", "10", "20"],
         ["X_03", "10", "10", "20"]]

For ease of use and convenience, I would like to be able to pass a list of list of list as well:

have:

data = [[["B_01"], ["10"], ["10", "20"], ["10", "20"]],
             ["D_02", "10", "10", "20"],
             ["X_03", "10", "10", "20"]]

and then be able to "explode" it to make it like the following:

want:

data = [["B_01", "10", "10", "10"],
        ["B_01", "10", "10", "20"],
        ["B_01", "10", "20", "10"],
        ["B_01", "10", "20", "20"],
        ["D_02", "10", "10", "20"],
        ["X_03", "10", "10", "20"]]

I know it is possible to do so for a list of list with the product function of the itertools package:

import itertools
list(itertools.product(*data))

However,

1. How can I do the same for a list of list of list ?
2. How can I loop on the input to only explode the list of list of list ?

Answer 1

Use itertools.product only if the first item of row is a list:

final = []
for l in data:
    if isinstance(l[0], list):  # <- ["B01"]
        for c in itertools.product(*l[1:]):
            final.append(l[0] + list(c))
    else:
        final.append(l)

>>> final
[['B_01', '10', '10', '10'],
 ['B_01', '10', '10', '20'],
 ['B_01', '10', '20', '10'],
 ['B_01', '10', '20', '20'],
 ['D_02', '10', '10', '20'],
 ['X_03', '10', '10', '20']]