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This tutorial illustrates how to access match metrics. The following is covered:

• How to retrieve device Id.
• How to retrieve match method.
• How to retrieve difference.
• How to retrieve rank.

Getting started example of using 51Degrees device detection match metrics information. The example shows how to:

1. Set the various settings for 51Degrees detector

   												
   my $filename = "51Degrees-LiteV3.2.dat";
   my $propertyList = "IsMobile"
   my $cacheSize = 10000;
   my $poolSize = 20;
   
   												

									
my $provider = new FiftyOneDegrees::PatternV3::Provider(
	$dataFile,
	$properties,
	$cacheSize,
	$poolSize);

									

									
my $match = $provider->getMatch($userAgent)

									

									match->getDeviceId();
									

									match->getMethod();
									

									match->getDifference();
									

									match->getRank();
									

												
use FiftyOneDegrees::PatternV3;
use feature qw/say/;

my $filename = "../../data/51Degrees-LiteV3.2.dat";
my $propertyList = "IsMobile";
my $cacheSize = 10000;
my $poolSize = 20;

# User-Agent string of an iPhone mobile device.
my $mobileUserAgent = "Mozilla/5.0 (iPhone; CPU iPhone OS 7_1 like Mac OS X) ".
"AppleWebKit/537.51.2 (KHTML, like Gecko) 'Version/7.0 ".
"Mobile/11D167 Safari/9537.53";

# User-Agent string of Firefox Web browser version 41 on desktop.
my $desktopUserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64; rv:41.0) ".
"Gecko/20100101 Firefox/41.0";

# User-Agent string of a MediaHub device.
my $mediaHubUserAgent = "Mozilla/5.0 (Linux; Android 4.4.2; X7 Quad Core ".
"Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 ".
"Chrome/30.0.0.0 Safari/537.36";

# Initialises the device detection provider with the settings declared above.
# This uses Lite data file. For more info
# see:
# <a href="https://51degrees.com/compare-data-options">compare data options
# </a>

my $provider = new FiftyOneDegrees::PatternV3::Provider(
    $filename,
    $propertyList,
    $cacheSize,
    $poolSize);

# output_metrics function. Takes a match object as an argument and
# prints the match metrics relating to the specific match.

sub output_metrics {
    my $match = $_[0];
    my $deviceId = $match->getDeviceId();
    my $method = $match->getMethod();
    my $difference = $match->getDifference();
    my $rank = $match->getRank();

    say "   Device Id: $deviceId";
    say "   Match Method: $method";
    say "   Difference: $difference";
    say "   Rank: $rank";

    return;
}

say "Staring Gettings Started Match Metrics Example.";

# Carries out a match with a mobile User-Agent.
say "\nMobile User-Agent: $mobileUserAgent";
my $match = $provider->getMatch($mobileUserAgent);
output_metrics($match);

# Carries out a desktop with a mobile User-Agent.
say "\nDesktop User-Agent: $desktopUserAgent";
my $match = $provider->getMatch($desktopUserAgent);
output_metrics($match);

# Carries out a MediaHub with a mobile User-Agent.
say "\nMediaHub User-Agent: $mediaHubUserAgent";
my $match = $provider->getMatch($mediaHubUserAgent);
output_metrics($match);


												

Match metrics is an additional piece of information about each match result. It can help developers spot fake User-Agents and determine the general level of confidence the detector has in the current detection results.

Device metrics consists of four parts: device Id, detection method, difference and rank.

Device Id is composed of four components, each represented as a number and separated by the hyphen symbol. Numbers correspond to profile IDs the detector has selected for that particular component. The four components are: hardware, software, browser and crawler. For more information please see the 51Degrees Data Model .

The detection method provides information on what algorithm was used for this particular detection and difference indicates by how much the provided User-Agent is different to the best signatures found in the data file. The larger the number the less confident the detector is. Difference for the 'exact' method is always zero. Difference for the 'none' detection method is irrelevant. For more information see the How Device Detection Works page.

Rank value tells you how popular the identified device is. The lower the value the more popular the device. Popularity is derived by 51Degrees based on our observed usage level.

Other uses for match metrics include:

• Ranking devices by popularity. Best used in conjunction with other tutorials to rank the results based on the general device popularity.
• Storing device Id for analytics instead of individual profiles.

The Lite data file contains 446,634 device combinations, whilst Premium and Enterprise contain 940,018 and 1,407,838 device combinations respectively. A larger set of device combinations leads to the 'exact' detection method being used more frequently and the rank providing a more accurate value.