# Convert an array of letters into numbers

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Ivan Mich on 30 Jan 2021
Commented: Walter Roberson on 31 Jan 2021
I would like to convert an array of letters into numbers. Based on this code:
Alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
numbers = [3,6,12,1,1,3]
letters = Alphabet(numbers)
I would like to make the reverse of this. I mean I want to find eg 'HELLO' to which numbers correspont based on the above code.
Stephen Cobeldick on 30 Jan 2021

Walter Roberson on 30 Jan 2021
Alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
Alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
[~, HelloNumbers] = ismember('HELLO', Alphabet)
HelloNumbers = 1×5
8 5 12 12 15
Map(Alphabet) = 1:length(Alphabet);
Map('HELLO')
ans = 1×5
8 5 12 12 15
Walter Roberson on 31 Jan 2021
Alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZÀÈÌÒÙÁÉÍÓÚÄËÏÖŸ';
Map(Alphabet(1:26)) = 1:26;
Map(Alphabet(27:end)) = Map('AEIOUAEIOUAEIOY');
Map('HÈLLÖ')
ans = 1×5
8 5 12 12 15

Ive J on 30 Jan 2021
Edited: Ive J on 30 Jan 2021
One way would be Map object:
alph = 'A':'Z';
num = 1:numel(alph); % or whatever
M = containers.Map(string(alph'), num);
term = 'HELLO';
arrayfun(@(x) M(x), string(term')).'
ans =
8 5 12 12 15