Translate nd array

Question

In python I have a nd array like this:

0 0 1
1 0 1
0 1 1
0 0 0

I know that the first position is “a”, second is “b”, and so on.

How can I transform “ones” to “as”, “bs”, … ?

Nothing yet. Not a clue.

Answer 1

I believe you might want to use array indexing:

a = np.array([[0,0,1],
              [1,0,1],
              [0,1,1],
              [0,0,0]])

out = np.array(['a', 'b'])[a]

Output:

array([['a', 'a', 'b'],
       ['b', 'a', 'b'],
       ['a', 'b', 'b'],
       ['a', 'a', 'a']], dtype='<U1')

replacing sequential 1s by a/b/c…

from string import ascii_lowercase

out = np.r_[[' '], list(ascii_lowercase)
            ][np.where(a.ravel(), a.cumsum(), 0).reshape(a.shape)]

Output:

array([[' ', ' ', 'a'],
       ['b', ' ', 'c'],
       [' ', 'd', 'e'],
       [' ', ' ', ' ']], dtype='<U1')