python - Parallelly looping over different lengths

Question

The idea is while iterating over a dictionary variable's each key, to take the first integer from each key, then in the next iteration, each key's second integer should be taken from the list, then only the third integer from each key, and so on.

I have the desired output, however, I would like to make it as universal as possible. Meaning that, instead of a static index order application, I would like two parallel loops. (probably izip is the solution)

My code:

dictionary = {0:[9, 9, 10, 8, 8, 8, 8], 1: [12,9,8,9,9,6,7], 2:[12, 12, 12, 10, 8, 9, 6], 3:[11, 10, 9, 12, 11, 10, 9]}

horizontal_dict = {}      
l1 = [] 
l2 = [] 
l3 =[] 
l4 = [] 
l5 =[] 
l6= []
l7 = []
for i in range(len(dictionary)):
    l1.append(dictionary[i][0])
    l2.append(dictionary[i][1])
    l3.append(dictionary[i][2])
    l4.append(dictionary[i][3])
    l5.append(dictionary[i][4])
    l6.append(dictionary[i][5])
    l7.append(dictionary[i][6])
    
    horizontal_dict[1] = l1
    horizontal_dict[2] = l2
    horizontal_dict[3] = l3
    horizontal_dict[4] = l4
    horizontal_dict[5] = l5
    horizontal_dict[6] = l6
    horizontal_dict[7] = l7        

Result of dictionary:

dictionary
Out[38]: 
{0: [9, 9, 10, 8, 8, 8, 8],
 1: [12, 9, 8, 9, 9, 6, 7],
 2: [12, 12, 12, 10, 8, 9, 6],
 3: [11, 10, 9, 12, 11, 10, 9]}

Desired result:

horizontal_dict
Out[37]: 
{1: [9, 12, 12, 11],
 2: [9, 9, 12, 10],
 3: [10, 8, 12, 9],
 4: [8, 9, 10, 12],
 5: [8, 9, 8, 11],
 6: [8, 6, 9, 10],
 7: [8, 7, 6, 9]}

question from:https://stackoverflow.com/questions/66050994/parallelly-looping-over-different-lengths

Answer 1

Use loops:

dictionary = {
    0: [9, 9, 10, 8, 8, 8, 8],
    1: [12, 9, 8, 9, 9, 6, 7],
    2: [12, 12, 12, 10, 8, 9, 6],
    3: [11, 10, 9, 12, 11, 10, 9, 13]
}

new = {}

for n in range(max(len(v) for v in dictionary.values())):
    new[n] = []
    for k, lst in dictionary.items():
        if n < len(lst):
            new[n].append(lst[n])
        else:
            # no element at index n
            # use a default value!
            new[n].append(-1)

print(new)

Out:

{0: [9, 12, 12, 11],
 1: [9, 9, 12, 10],
 2: [10, 8, 12, 9],
 3: [8, 9, 10, 12],
 4: [8, 9, 8, 11],
 5: [8, 6, 9, 10],
 6: [8, 7, 6, 9],
 7: [-1, -1, -1, 13]}