Test::Approx - compare two things for approximate equality
use Test::Approx 'no_plan'; is_approx( 'abcd', 'abcd', 'equal strings' ); is_approx( 1234, 1234, 'equal integers' ); is_approx( 1.234, 1.234, 'equal decimal numbers' ); is_approx( '1.234000', '1.234', 'equal decimal numbers, extra zeros' ); is_approx( 1.0, 1, 'equal decimal number & integer' ); is_approx( 'abcdefgh', 'abcdefg', 'approx strings' ); is_approx( 1, 1.001, 'approx given decimal number & integer' ); is_approx( 51.60334, 51.603335, 'approx decimal numbers' ); # default Levenshtein edit tolerance is 5% of avg string length: is_approx( 'abcdefg', 'abcgfe', 'str tolerance' ); # fail # default difference tolerance is 5% of first number: is_approx( 1, 1.04, 'num tolerance' ); # fail is_approx( 1, 1.05, 'num tolerance' ); # fail # default difference tolerance is 5% of first integer, or 1: is_approx( 1, 2, 'int tolerance' ); # pass is_approx( 100, 105, 'int tolerance' ); # pass is_approx( 100, 106, 'int tolerance' ); # fail # you can set the tolerance yourself: is_approx( 'abcdefg', 'abcgfe', 'diff strings', '50%' ); # pass # you can set tolerance as a number too: is_approx( 'abcdefg', 'abcgfe', 'diff strings', 6 ); # you can force compare as string, number, or integer: is_approx_str( '1.001', '1.901', 'pass as string' ); is_approx_num( '1.001', '1.901', 'fail as num' ); is_approx_int( '1.001', '1.901', 'pass as int' ); # not rounded!
This module lets you test if two things are approximately equal. Yes, that sounds a bit wrong at first - surely you know if they should be equal or not? But there are actually valid cases when you don't / can't know. This module is meant for those rare cases when close is good enough.
Tests if two scalars $arg1
& $arg2
are approximately equal by using one of: "is_approx_str", "is_approx_num" or is_approx_int.
$test_name
defaults to 'arg1' =~ 'arg2'
.
$tolerance
is used to determine how different the scalars can be, it defaults to 5%
. It can also be set as a number representing a threshold. To determine which:
$tolerance = '6%'; # threshold = calculated at 6% $tolerance = 0.06; # threshold = 0.06
See the individual functions to determine how $tolerance
is used.
Tests if $str1
is approximately equal to $str2
by using Text::LevenshteinXS to compute the edit distance between the two strings, and comparing that to $tolerance
.
$tolerance
is used to determine how many edits are allowed before the comparison test fails. If a percentage is given, the edit distance threshold will be set to x%
of the average lengths of the two strings. eg:
$edit_threshold = int( $x_percent * avg(length($str1), length($str2)) );
If that's less than 0, it defaults to 1
. You can also pass $tolerance
in as an number. To avoid confusion:
$tolerance = '6%'; # threshold = 6% of avg strlen $tolerance = 0.06; # threshold = int( 0.06 ) = 0
Tests if $num1
is approximately equal to $num2
by calculating the distance between them and comparing that to $tolerance
.
If $tolerance
is a percentage, the distance threshold will be set to x%
of the first number, eg:
$threshold = $x_percent * $num1;
Note that this can be 0 > $t > 1, which is probably what you want. To avoid confusion:
$tolerance = '6%'; # threshold = 6% of $num1 $tolerance = 0.06; # threshold = 0.06
Tests if $int1
is approximately equal to $int2
by calculating the distance between them and comparing that to $tolerance
. This is slightly different to "is_approx_num" as all fractions are removed.
If $tolerance
is a percentage, the distance threshold will be set to x%
of the first integer, or 1. Eg:
$threshold = int( $x_percent * $int1 ) || 1;
To avoid confusion:
$tolerance = '6%'; # threshold = 6% of $int1 $tolerance = 0.06; # threshold = 0.06
is_approx
, is_approx_str
, is_approx_num
, is_approx_int
Steve Purkis <spurkis@cpan.org>
Copyright (c) 2008-2010 Steve Purkis. Released under the same terms as Perl itself.