python 3d list manipulation-CodePudding

I have a 3d list aa = [[[2, 3, 4, 5], [ 6, 7, 8, 9]], [[11, 12, 14, 15]]], which consists of two 2d lists how do I get this result [[2, 6], [11]] the first element of each sub list.

b = []
for i, row in enumerate(aa):
  for j, rr in enumerate(row):
    b.append(rr[0])

gives [2,6,11]

CodePudding user response：

You can do it with a list comprehension:

[[i[0] for i in j] for j in aa]

Output:

[[2, 6], [11]]

CodePudding user response：

Just store each first element in a sublist and merge those sublists to get your result

arr here is your input array

ret = []
for twoD in arr:
    temp=[]
    for oneD in twoD:
        temp.append(oneD[0])
    ret.append(temp)
print(ret)

Output

[[2, 6], [11]]