Seperate 2D array to nested list

Seperate 2D array to nested list.

Exercise : 2D array --> [[3 items],[1 item]]

1. 2-d array

df_24months.values

>>>

array([[ 2. ,  2. ,  4. ,  3. ,  4. ,  2. ,  3. ,  2. ,  3. ,  1. ,  4. ,
         2. ,  1.5,  3. ,  3. ,  2.5,  2. ,  2. ,  1. ,  0. ,  3.5,  1. ,
         1. ,  2. ],
       [ 2. ,  1. ,  0. ,  1. , 10. ,  7. ,  3. ,  6. ,  4. ,  7. , 15. ,
        10. , 12. , 10. ,  5. ,  9. ,  6. ,  5. , 12. ,  6. ,  4. ,  3. ,
         1. ,  1. ],
       [ 6. ,  6. ,  6. , 14. , 24. , 11. , 10. , 12. , 22. ,  8. , 19. ,
        10. , 11. , 12. ,  4. ,  5. ,  3. ,  4. ,  4. , 10. ,  3. ,  3. ,
         8. ,  2. ]])
         
2. Seperate to nested lists.

windows_size=3
target_size = 1

train_set_list = []


for line in df_24months.values:
    for start in range(len(line) - (windows_size + target_size - 1)):
        i = start
        j = start + windows_size
        k = start + windows_size + target_size
        
        x_val = line[i: j].tolist()
        y_val = line[j: k].tolist()
        
        train_set_list.append([x_val, y_val])
        
train_set_list[:2]

>>>

[[[2.0, 2.0, 4.0], [3.0]], [[2.0, 4.0, 3.0], [4.0]]]