How can I duplicate all elements in an 2D array?

How can I duplicate all elements in an 2D array?
The order matters.

For example:

arr = [
  ["d", "a", "c"],
  ["b", "l", "a"],
  ["d", "u", "h"],
]

# do something

print(arr)
# Output: [
#  ["d", "d", "a", "a", "c", "c"],
#  ["b", "b", "l", "l", "a", "a"],
#  ["d", "d", "u", "u", "h", "h"],
# ]

>Solution :

Here is one way to do so using list comprehension:

new_arr = [[element for item in sublist for element in (item, item)] for sublist in arr]
print(new_arr)
# [['d', 'd', 'a', 'a', 'c', 'c'], ['b', 'b', 'l', 'l', 'a', 'a'], ['d', 'd', 'u', 'u', 'h', 'h']]

An alternative using for loops would be:

new_arr = []
for sublist in arr:
    new_sublist = []
    for item in sublist:
        new_sublist.extend([item, item])
    new_arr.append(new_sublist)
print(new_arr)