How to create Dict from array in python

Question

Have:

keys = ['a', 'b','c','d']

numpy array....

array = numpy.array([[1, 2, 3, 5], [6, 7, 8, 10], [11, 12, 13, 15]])

want

my_dict = {'a': [1,6,11], 'b': [2,7,12], 'c': [3,7,13], 'd': [5,10,15]}

Answer 1

Transpose the array, zip() the keys with the result and convert to a dict:

dict(zip(keys, zip(*array)))

Since array is a NumPy array, you can also use

dict(zip(keys, array.T)))

Answer 2

keys = ['a', 'b','c','d']
vals = [[1, 2, 3, 5], [6, 7, 8, 10], [11, 12, 13, 15]]
dict(zip(keys, zip(*vals)))

{'a': (1, 6, 11), 'c': (3, 8, 13), 'b': (2, 7, 12), 'd': (5, 10, 15)}

It's useful to see what is happening when you zip(*) an object, it's quite a useful trick:

zip(*vals)

[(1, 6, 11), (2, 7, 12), (3, 8, 13), (5, 10, 15)]

It looks (and you'll see it another answer) like the transpose! There is a 'gotcha, here. If one of the lists is shorter than the others, zip(*) will stop prematurely:

 vals = [[1, 2, 3, 5], [6, 7, 8, 10], [11, 12, 13]]
 zip(*vals)

 [(1, 6, 11), (2, 7, 12), (3, 8, 13)]