Understanding - Advanced, exercise 20

Text

The variable the variable my_mat_l contains a list of integers where each number is a digit of a matriculation number (e.g. [0, 0, 0, 0, 1, 2, 3, 4, 5, 6]). The variable my_fn contains the string of a full name in lower case (e.g. "john doe"). Study the execution of the following function when it is called as follows: f(my_mat_l, my_fn).

def f(mat, name):
    name_l = list(name)

    uni = set()
    for i in mat:
        if i < len(name):
            uni.add(i)
    
    if len(uni) % 2 > 0:
        uni.remove(0)
    
    sl = list()
    for i in uni:
        pos = 0
        for j in sl:
            if j < i:
                pos = pos + 1
        sl.insert(pos, i)

    sl_last = len(sl) - 1
    for i in range(len(sl) // 2):
        s = sl[i]
        e = sl[sl_last]
        tmp = name_l[s]
        name_l[s] = name_l[e]
        name_l[e] = tmp
        sl_last = sl_last - 1
    
    return "".join(name_l)

Hints

The function f is organised in three blocks. The first block takes a selection of the numbers in the input matriculation number. The second block sorts such number in a precise order. The third block swaps elements in the list obtained from the name in input.

Additional material

The runnable Python file is available online. You can run it executing the command python exercise_20.py in a shell, and then following the instructions on screen to specify the intended input.