pgffor map elements

Question

pgffor's foreach can take an "array" of elements. I need to map those elements using another array(a lookup table) because I need both the elements and there mapped value.

e.g., suppose I an doing some cryptography and have letters mapped to numbers in some non-standard way

\foreach \i in {a,b,c,d,e}
{
 \i = \lookup{\i}{\data}
}

where data is, I guess some type of associative array that says stuff like

a = 12, b = 16, c = 3, d = 9, e = 19

which the foreach will then print

a = 12
b = 16
c = 3
d = 9
e = 19

I also can simply another array and I want to step through them simultanously, for of like

\foreach \i,\j in {a,b,c,d,e} , {12,16,3,9,19}
{
 \i = \j
}

(I do not want some type of nested loops, that is not what I'm trying to do)

The easiest solution the better. I'm not trying to do anything extremely complex

Answer 1

In the question, you have some options in mind and things you might not do but the question is not clear at all. I'm guessing something of the following.

\documentclass{article}
\usepackage{pgffor,pgfmath}

% Got some array from Excel via =randbetween(1-26)
\def\Sometwentysixnumarray{{11,4,8,12,17,20,13,9,12,16,4,19,6,11,4,26,10,13,14,15,15,1,5,1,26,14}}

\begin{document}
\foreach \x[count=\xi from 0] in {a,...,z}{
\pgfmathparse{\Sometwentysixnumarray[\xi]}
\x = \pgfmathresult, 
}
\end{document}