From: Robert Klemme <shortcutter@...>
Date: 2007-03-16T06:55:05+09:00
Subject: Re: Need help converting Perl to Ruby (detecting integers and decimals in strings)

On 15.03.2007 22:39, Paul wrote:
> I am trying to convert a Perl script to Ruby and have been having some
> difficulty along the way (mostly because I don't know Perl).
> 
> I am currently stumped on one particular line in the old Perl script:
> ---
> 	foreach (@rawfields) {if ($_ > 0){$_ = int($_*100)/100}}
> ---
> 
> Background context:  @rawfields is an array that holds the contents of
> an imported line from a text file.  Here are some sample lines from
> the input file:
> ---
> "0"	"0"	"0"	"0"	"0"	"0"	"Bar"
> "5.66666"	"0"	"3.566662"	"1.383332"	"6"	"0"	"Foo"
> ---
> 
> My guess is that the Perl line iterates through each of the elements
> in the array and rounds any integers to 2 decimals.
> 
> This raises a few problems for me.
> 
> 1) How can I easily tell if the (string) value in each array element
> is an integer or has a decimal value?
> 
> => The desired output for text file line 2 is :
> ---
> "5.67"   "0"   "3.57"   "1.38"   "6"   "0"   "Foo"
> ---
> 
> 
> I tried the following in Ruby:
> ---
> @rawfields.each_index do |x|
> 	if ( @rawfields[x].to_f > 0 )
> 		@rawfields[x] = ( (( @rawfields[x].to_f * 100 ).round.to_i ).to_f /
> 100 ).to_s
> 	end
> end
> ---
> 
> But it produces the following output:
> ---
> "5.67"  "0"  "3.57"  "1.38"  "6.0"  "0"  "Foo"
> ---
> 
> ...which is close, but not quite what I want.  My output file now has
> values like 1.0, 5.0, 62.0, etc.  If it's an integer, I don't want to
> see the decimal.
> 
> Can anyone suggest an improvement to my code or a better translation
> from Perl?
> 
> TIA.  Paul.
> 

How about

irb(main):005:0> fields = %w{5.6666 0 Foo}
=> ["5.6666", "0", "Foo"]
irb(main):006:0> fields.map {|v| sprintf("%4.2f", Float(v)) rescue v}
=> ["5.67", "0.00", "Foo"]

This uses the fact that Float() will throw if the string is not a valid 
number.  If you really need "0" instead of "0.00" you could apply 
another test.  If you need the quotes you could do

irb(main):008:0> puts fields.map {|v| (sprintf("%4.2f", Float(v)) rescue 
v).inspect}.join(" ")
"5.67" "0.00" "Foo"

Kind regards

	robert