A 3-D List means that we need to make a list that has three parameters to it, i.e., (a x b x c), just like a 3 D array in other languages. In this program we will try to form a 3-D List with its content as “#”. Lets look at these following examples:
Input : 3 x 3 x 3 Output : [[['#', '#', '#'], ['#', '#', '#'], ['#', '#', '#']], [['#', '#', '#'], ['#', '#', '#'], ['#', '#', '#']], [['#', '#', '#'], ['#', '#', '#'], ['#', '#', '#']]] Input : 5 x 3 x 2 Output : [[['#', '#', '#', '#', '#'], ['#', '#', '#', '#', '#'], ['#', '#', '#', '#', '#']], [['#', '#', '#', '#', '#'], ['#', '#', '#', '#', '#'], ['#', '#', '#', '#', '#']]]
Python3
# Python program to print 3D list# importing pretty printedimport pprintdef ThreeD(a, b, c): lst = [[ ['#' for col in range(a)] for col in range(b)] for row in range(c)] return lst # Driver Codecol1 = 5col2 = 3row = 2# used the pretty printed functionpprint.pprint(ThreeD(col1, col2, row)) |
[[['#', '#', '#', '#', '#'], ['#', '#', '#', '#', '#'], ['#', '#', '#', '#', '#']], [['#', '#', '#', '#', '#'], ['#', '#', '#', '#', '#'], ['#', '#', '#', '#', '#']]]
Refer pprint() to get more insight into this topic. Now let’s suppose we need to merge two 3D lists into one.
Python3
# Python program to merge two 3D list into one# importing pretty printedimport pprintdef ThreeD(a, b, c): lst1 = [[ ['1' for col in range(a)] for col in range(b)] for row in range(c)] lst2= [[ ['2' for col in range(a)] for col in range(b)] for row in range(c)] # Merging using "+" operator lst = lst1+lst2 return lst # Driver Codecol1 = 3col2 = 3row = 3# used the pretty printed functionpprint.pprint(ThreeD(col1, col2, row)) |
[[['1', '1', '1'], ['1', '1', '1'], ['1', '1', '1']], [['1', '1', '1'], ['1', '1', '1'], ['1', '1', '1']], [['1', '1', '1'], ['1', '1', '1'], ['1', '1', '1']], [['2', '2', '2'], ['2', '2', '2'], ['2', '2', '2']], [['2', '2', '2'], ['2', '2', '2'], ['2', '2', '2']], [['2', '2', '2'], ['2', '2', '2'], ['2', '2', '2']]]
Using nested for loops:
Approach:
In this approach, we can create a 3D list using nested for loops. We will start by creating an empty list and then using three for loops to iterate over the dimensions and append the ‘#’ character to the list.
Create an empty list lst to hold the 3D list.
Loop through the range x to create the first dimension of the 3D list.
Within the x loop, create an empty list lst_2d to hold the 2D list for each x element.
Loop through the range y to create the second dimension of the 3D list.
Within the y loop, create an empty list lst_1d to hold the 1D list for each y element.
Loop through the range z to create the third dimension of the 3D list.
Within the z loop, append the value ‘#’ to the 1D list lst_1d for each z element.
After the z loop, append the 1D list lst_1d to the 2D list lst_2d.
After the y loop, append the 2D list lst_2d to the 3D list lst.
After the x loop, return the 3D list lst.
Python3
def create_3d_list_1(x, y, z): lst = [] for i in range(x): lst_2d = [] for j in range(y): lst_1d = [] for k in range(z): lst_1d.append('#') lst_2d.append(lst_1d) lst.append(lst_2d) return lst# Input 1x = 3y = 3z = 3output_1 = create_3d_list_1(x, y, z)print(output_1)# Input 2x = 5y = 3z = 2output_2 = create_3d_list_1(x, y, z)print(output_2) |
[[['#', '#', '#'], ['#', '#', '#'], ['#', '#', '#']], [['#', '#', '#'], ['#', '#', '#'], ['#', '#', '#']], [['#', '#', '#'], ['#', '#', '#'], ['#', '#', '#']]] [[['#', '#'], ['#', '#'], ['#', '#']], [['#', '#'], ['#', '#'], ['#', '#']], [['#', '#'], ['#', '#'], ['#', '#']], [['#', '#'], ['#', '#'], ['#', '#']], [['#', '#'], ['#', '#'], ['#', '#']]]
Time Complexity: O(n^3)
Space Complexity: O(n^3)
