How i can setup every n elements as dict values in dict comprehension

Question

An example:

data_1 = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36]
data_2 = ['key1','key2','key3','key4','key5','key6','key7','key8','key9','key10','key11','key12']
data_3 = {'123':{'a':1},'222':{'b':2}, '333':{'b':3}}

I need setup this list to dict keys by next condition, every 12 elements from data_1 should be values of every keys from data_2 and this dict should be value of key from data 3.

Expected output:

{'123':{'key1':1,'key2':2,'key3':3,'key4':4,'key5':5,'key6':6,'key7':7,'key8':8,'key9':9,'key10':10,'key11':11,'key12':12},
{'222':{'key1':13,'key2':14,'key3':15,'key4':16,'key5':17,'key6':18,'key7':19,'key8':20,'key9':21,'key10':22,'key11':23,'key12':24},
{'333':{'key1':25,'key2':26,'key3':27,'key4':28,'key5':29,'key6':30,'key7':31,'key8':32,'key9':33,'key10':34,'key11':35,'key12':36}

My attempt:

    result = {
        key: dict(zip(data_2,data_1) for key, value in data_3.items()
    }

My result:

{'123': {'key1': 1, 'key2': 2, 'key3': 3, 'key4': 4, 'key5': 5, 'key6': 6, 'key7': 7, 'key8': 8, 'key9': 9, 'key10': 10, 'key11': 11, 'key12': 12}, '222': {'key1': 1, 'key2': 2, 'key3': 3, 'key4': 4, 'key5': 5, 'key6': 6, 'key7': 7, 'key8': 8, 'key9': 9, 'key10': 10, 'key11': 11, 'key12': 12}, '333': {'key1': 1, 'key2': 2, 'key3': 3, 'key4': 4, 'key5': 5, 'key6': 6, 'key7': 7, 'key8': 8, 'key9': 9, 'key10': 10, 'key11': 11, 'key12': 12}}

I understand what mistake in this part of statement:

key: dict(zip(data_2,data_1)

How i can reach result which I expected ?

Answer 1

An approach is to use the fact that zip, will only iterate until the smaller iterable is consumed, so you can do the following:

iterable_data1 = iter(data_1)

result = {key: dict(zip(data_2, iterable_data1)) for key in data_3}

for key, value in result.items():
    print(key, value)

This very efficient, because it do not create any additional list. Also, you could do:

result = {key: dict(zip(data_2, data_1[12 * i:])) for i, key in enumerate(data_3)}

for key, value in result.items():
    print(key, value)

Output

123 {'key1': 1, 'key2': 2, 'key3': 3, 'key4': 4, 'key5': 5, 'key6': 6, 'key7': 7, 'key8': 8, 'key9': 9, 'key10': 10, 'key11': 11, 'key12': 12}
222 {'key1': 13, 'key2': 14, 'key3': 15, 'key4': 16, 'key5': 17, 'key6': 18, 'key7': 19, 'key8': 20, 'key9': 21, 'key10': 22, 'key11': 23, 'key12': 24}
333 {'key1': 25, 'key2': 26, 'key3': 27, 'key4': 28, 'key5': 29, 'key6': 30, 'key7': 31, 'key8': 32, 'key9': 33, 'key10': 34, 'key11': 35, 'key12': 36}

The idea, of the second approach, is for each key in data_3 move the pointer for data_1 12 places.