From: Tim Hunter <cyclists@...>
Date: 2006-02-15T09:03:27+09:00
Subject: Re: simple programming q

grrr wrote:
> I am a ruby newbie. I want to make a simple script that replaces certain
> characters in a block of text with specific other characters.
> 
> I am wondering what kind of loop or algo is thought to be most effective
> for this kind of work.. 
> Maybe go through the block of text with a hashing table and replace
> each 'hit'? Would this be reasonable approach?
> 
> #example pseudocode idea
> blokoftxt = 'Theres some text in block.'
> replacekey = { 'T' = 'W', 'a' = 'o', 'o' = 'a' }
> 
> blokoftxt.each ( if equal to a replacekey, replace with key value )
> 
> 
> This would mean going through each character in the textblock. I guess one
> could conversely go through the replacekey array and match to the
> textblock?? Which way to go?
> 
> J Von Rubiginner
> 
> 


text = <<-ENDTEXT
The Owl and the Pussy-cat went to sea
     In a beautiful pea green boat,
They took some honey, and plenty of money,
     Wrapped up in a five pound note.
The Owl looked up to the stars above,
     And sang to a small guitar,
'O lovely Pussy! O Pussy my love,
       What a beautiful Pussy you are,
           You are,
           You are!
What a beautiful Pussy you are!'
ENDTEXT

replace_key = { 'O' => 'd', 'P' =>  'w', 'b' => 'x'}
new_text = text.gsub(/[#{replace_key.keys.join}]/) {|match|
	replace_key[match]
}
puts new_text

The result is:

The dwl and the wussy-cat went to sea
     In a xeautiful pea green xoat,
They took some honey, and plenty of money,
     Wrapped up in a five pound note.
The dwl looked up to the stars axove,
     And sang to a small guitar,
'd lovely wussy! d wussy my love,
       What a xeautiful wussy you are,
           You are,
           You are!
What a xeautiful wussy you are!'