How to use the index and substr funtions that are used in SAS to do it in R. See below codes given in SAS
if index(number,'%75') then do;
i=0;
do while(index(number,'%75') > 0);
i+1;
pos=index(number,'%75');
val=input(substr(number,_pos+3,2), $hex2.);
substr(number, _pos,3)='^^^';
substr(number, _pos+3,2)='^'||_val;
end;
number=transtrn(number,'^^^^',trimn(''));
number=transtrn(number,'^^^',trimn('%75'));
end;