String Processing
Hashes
In this lesson the student will learn how to:
li>Know how to create and use hashes
- Know how extract the keys and values from a hash
- Know how to extract a single value from a hash
By the end of this lesson the student will be able to:
Write an amino acid quiz script
using a hash.
Protein Structure
Amino acids are the building blocks of proteins. Proteins, however, are not
merely strings of amino acids. Their structure can be looked at from the
following perspectives:
- Primary Structure - Amino acid sequence
- Secondary Structure - Local folds within a chain or the motifs formed by
amino acids which are near to each other.
- Tertiary Structure - Overall shape of a polypeptide or the way it folds
once local motifs have formed.
- Quarternary Structure - The way different polypeptides attach to one
another to form functional complexes.
Hashes
<![CDATA[
#!/usr/bin/perl
%ES = (
'one' => 'uno',
'two' => 'dos',
'three' => 'tres',
'four' => 'quatro',
'five' => 'cinco',
'six' => 'seis'
);
@eng = keys(%ES);
@span = values(%ES);
#not necessary in the order as shown above!
print "ENGLISH: @eng\n";
print "SPANISH: @span\n";
foreach $item (keys ( %ES)){
print "$item --> $ES{$item}\n";
}
#individual item:
print "------\n";
print "one --> $ES{'one'}\n";
]]>
Take a look at the example above and the example below and make sure you
understand how to access an item in a hash and note that there are two ways
to initialize a hash. Also make sure that you figure out what the keys and
values functions do. Note that each returns an array.
<![CDATA[
#!/usr/bin/perl
%ah = ( "fred", 17, "wilma", 22, "dino", 5, "pebbles", 3);
foreach $item (keys %ah){
print "$item --> $ah{$item}\n";
}
]]>
ASSIGNMENT:
Write a script which quizzes the user on the amino acid names and symbols.
When presented with a symbol, the user must enter the name of the
corresponding amino acid. The quiz script must use a hash and the amino
acids must be presented in random order.