I have two arrays, for example:
a = [a, b, c, d, e, f, g]
b = [1, 2, 3, 4, 5, 6, 7]
My first array is then splitted in a dictionary, in the following form:
dict = {key1: [a, c, e], key2: [f, g], key3: [b, d]}
I would like to get another dictionary, having the same partition but with the elements of array b:
dict = {key1: [1, 3, 5], key2: [6, 7], key3: [2, 4]}
In other words, I would like a correspondence between arrays a and b
The brute force way to do this is to use index() to look up the index of each element in the sublists of the dict and use that index to lookup the value in b.
You can do that in a single dict comprehension with something like:
a = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
b = [1, 2, 3, 4, 5, 6, 7]
d = {'key1': ['a', 'c', 'e'], 'key2': ['f', 'g'], 'key3': ['b', 'd']}
{k: [b[a.index(l)] for l in v] for k, v in d.items()}
# {'key1': [1, 3, 5], 'key2': [6, 7], 'key3': [2, 4]}
You could make things a little more efficient by creating a lookup dict that maps letters to the indices of a so you don't need to iterate a the index each time with
a_lookup = {l: i for i, l in enumerate(a)}
# then:
{k: [b[a_lookup[l]] for l in v] for k, v in d.items()}
Using index and list comprehension:
a = [a, b, c, d, e, f, g]
b = [1, 2, 3, 4, 5, 6, 7]
dict1 = {key1: [a, c, e], key2: [f, g], key3: [b, d]}
dict2 = {}
for key in dict1:
dict2[key] = [b[a.index(i)] for i in dict1[key]]
How this works:
dict1dict2b as of that in a