lenti248 [~/perltest]>more rand2hash.pl
#!/usr/bin/perl -w
#

# assign keys and values to a hash
# keys = 1 letter codes, values = aa names
%aa_codes = ("A" => "alanine", "R" => "arginine", "D" => "aspartate",
"N" => "asparagine", "C" => "cysteine", "E" => "glutamate",
"Q" => "glutamine", "G" => "glycine", "H" => "histidine",
"I" => "isoleucine", "L" => "leucine", "K" => "lysine",
"M" => "methionine", "F" => "phenylalanine", "P" => "proline",
"S" => "serine", "T" => "threonine", "Y" => "tyrosine",
"W" => "tryptophan", "V" => "valine");

# seed random number generator
srand ; # equivalent to srand (time) - a different seed each time

# start main program loop
$again = "y";
until ($again ne "y") {

# print random name and code
@allcodes = keys (%aa_codes);
$code = $allcodes [int (rand (scalar @allcodes))];
print $aa_codes{$code}, "  ", $code, "\n\n";

# end main program loop
print "Again (y/n)? ";
chomp ($again = <STDIN>);
$again = lc ($again);
$again = substr ($again,0,1);
}

exit;

lenti249 [~/perltest]>perl rand2hash.pl
isoleucine  I

Again (y/n)? y
asparagine  N

Again (y/n)? y
serine  S

Again (y/n)? y
tryptophan  W

Again (y/n)? y
glutamate  E

Again (y/n)? n
lenti250 [~/perltest]>