I arrived here because I was looking to see how I could nest an arbitrary number of lists. There are a lot of explanations and specific examples above, but you can generalize N dimensional list of lists of lists of ... with the following recursive function:
import copy
def list_ndim(dim, el=None, init=None):
if init is None:
init = el
if len(dim)> 1:
return list_ndim(dim[0:-1], None, [copy.copy(init) for x in range(dim[-1])])
return [copy.deepcopy(init) for x in range(dim[0])]
You make your first call to the function like this:
dim = (3,5,2)
el = 1.0
l = list_ndim(dim, el)
where (3,5,2)
is a tuple of the dimensions of the structure (similar to numpy shape
argument), and 1.0
is the element you want the structure to be initialized with (works with None as well). Note that the init
argument is only provided by the recursive call to carry forward the nested child lists
output of above:
[[[1.0, 1.0], [1.0, 1.0], [1.0, 1.0], [1.0, 1.0], [1.0, 1.0]],
[[1.0, 1.0], [1.0, 1.0], [1.0, 1.0], [1.0, 1.0], [1.0, 1.0]],
[[1.0, 1.0], [1.0, 1.0], [1.0, 1.0], [1.0, 1.0], [1.0, 1.0]]]
set specific elements:
l[1][3][1] = 56
l[2][2][0] = 36.0+0.0j
l[0][1][0] = 'abc'
resulting output:
[[[1.0, 1.0], ['abc', 1.0], [1.0, 1.0], [1.0, 1.0], [1.0, 1.0]],
[[1.0, 1.0], [1.0, 1.0], [1.0, 1.0], [1.0, 56.0], [1.0, 1.0]],
[[1.0, 1.0], [1.0, 1.0], [(36+0j), 1.0], [1.0, 1.0], [1.0, 1.0]]]
the non-typed nature of lists is demonstrated above