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What's Covered

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.

Code and Explanation

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

  1. Instantiate the 51Degrees device detection provider.

    var provider = FiftyOneDegreesPatternV3.NewProvider(dataFile)
  2. Produce a match for a single HTTP User-Agent header

    var match = provider.GetMatch(userAgent)
  3. Obtain device Id: consists of four components separated by a hyphen symbol: Hardware-Platform-Browser-IsCrawler where each Component represents an ID of the corresponding Profile.

  4. Obtain match method: provides information about the algorithm that was used to perform detection for a particular User-Agent. For more information on what each method means please see: How device detection works

  5. Obtain difference: used when detection method is not Exact or None. This is an integer value and the larger the value the less confident the detector is in this result.

  6. Obtain signature rank: an integer value that indicates how popular the device is. The lower the rank the more popular the signature.

This example assumes you have the 51Degrees Go API installed correctly.
Full Source File
package main

import (

var matchMethod = []string {

// Location of data file.
var dataFile = "../data/51Degrees-LiteV3.2.dat"

// Provides access to device detection functions.
var provider =

// Which properties to retrieve
var properties = []string{"IsMobile", "PlatformName", "PlatformVersion"}

// User-Agent string of an iPhone mobile device.
var 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 " +

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

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

// output_metrics function. Takes a match object as an argument and
// prints the match metrics relating to the specific match.
func outputMetrics(match FiftyOneDegreesPatternV3.Match) {
    fmt.Println("   Id: ", match.GetDeviceId())
    fmt.Println("   Match Method: ", matchMethod[match.GetMethod()])
    fmt.Println("   Difference: ", match.GetDifference())
    fmt.Println("   Rank: ", match.GetRank())

func main() {
    fmt.Println("Starting Getting Started Match Metrics Example.\n")

    // Carries out a match with a mobile User-Agent.
    fmt.Println("Mobile User-Agent: ", mobileUserAgent)
    var match = provider.GetMatch(mobileUserAgent)

    // Carries out a match with a desktop User-Agent.
    fmt.Println("Desktop User-Agent: ", desktopUserAgent)
    match = provider.GetMatch(desktopUserAgent)

    // Carries out a match with a MediaHub User-Agent.
    fmt.Println("Media Hub User-Agent: ", mediaHubUserAgent)
    match = provider.GetMatch(mediaHubUserAgent)

Full Source File


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.