convert matrix string to matrix python

1arr = '[[1, 2], [3, 4], [5, 6]]'
2num_set = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]
3arr_list = list(arr)
4
5matrix = []
6row = []
7
8for i in range(0, len(arr_list)):
9    try:
10        if(len(row) == 2):
11            matrix.append(row)
12            row = []
13        if(int(arr_list[i]) in num_set):
14            row.append(int(arr_list[i]))
15    except:
16        continue
17
18print(matrix)