If statement for two different arrays in bash

I have two arrays, which are arrAlpha[] and arrPT[]. Array arrAlpha contains the Alphabets and array arrPT[] contains some of the plain letters.following is the code that i wrote in bash shell script to compare elements of both arrays and to store the position elements of arrPT[] in arrAlpha[] to array arrT[]. But when i run i feel like something is wrong in if statement to print out the elements in arrT[]. can anyone help me please?

     #!/bin/bash

     arrAlpha=(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z)

     arrPT=(E K N R S W )
     lenPT=${#arrPT}
     declare -A arrT
     q=0
     for((i=0; i<lenPT; i++)) do
         for((j=i; j<26; j++)) do
             if [  ${arrPT[$i]}  =  ${arrAlpha[$j]}  ]; then
                 arrT[$q]=$j % 26;
                 ((++q));
             fi
          done
     done

     echo ${arrAlpha[@]}
     echo ${arrPT[@]}
     echo ${arrT[@]}