matching a number

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi all, Is it possible to match a number with in +/- a few decimal places. For example my input value is 5.56, i search a list of true values (pattern match) if the values match then fine. However, if it doesnt match i want to match any numbers stored than are with +/- 0.1 of the input value. Is this possible?

$input = 5.56

open (FH, "<listofvalues");
while (<FH>) {
^/(S+\.S+).*/

if $1 == $in {print value in list}
else
increment $in by +/- 0.1 and search again
if match print value in list
otherwise print not in list
[download]

thanks

Comment on matching a number Download Code

Replies are listed 'Best First'.
Re: matching a number by tlm (Prior) on May 31, 2005 at 16:12 UTC
Why not just simple arithmetic for this? `while ( <FH> ) { chomp; if ( abs( $input - $_ ) <= 0.1 ) { print "Value in list\n"; last; } }` [download] Update: The original version of the above was overly complicated. I simplified it significantly, though the basic idea is the same. the lowliest monk	[reply] [d/l]
Re: matching a number by BigRare (Pilgrim) on May 31, 2005 at 16:18 UTC
It looks like what you want is to search for a range. Example: `if (($input - 0.1) <= $1 && $1 <= ($input + 0.1)) { <insert code here>; }` [download]	[reply] [d/l]
Re: matching a number by trammell (Priest) on May 31, 2005 at 16:35 UTC
Perhaps Test::Number::Delta meets your needs?	[reply]
Re: matching a number by chas (Priest) on May 31, 2005 at 16:38 UTC
If you actually need to extract the number with a regex you can use something like: `while(<F>){ /(\d+\.\d+)/; if (abs($1 - 5.56)<=.1) {print $1,"\n"} }` [download] (If there is more than one number on a line, you'll have to do something a little different, but it looks like that's not the case from your original code.) chas (Update: I'm now a little unhappy about this because I noticed that `abs(5.56-5.66)<=.1` returns false. I wonder if Test::Number::Delta as suggested by trammell is more reliable in this respect. From the docs it looks like it may not be, but I haven't tried it...)	[reply] [d/l] [select]
Re^2: matching a number by davidrw (Prior) on May 31, 2005 at 16:46 UTC
Minor tweak to make sure the $1 is used IFF the regex succeeds: `while(<F>){ next unless /(\d+\.\d+)/ && abs($1 - 5.56)<=.1; print $1,"\n"; }` [download]	[reply] [d/l]