PHP: gmp_hamdist - Manual (original) (raw)

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

gmp_hamdist — Hamming distance

Description

Parameters

num1

A GMP object, an int, or a string that can be interpreted as a number following the same logic as if the string was used in gmp_init() with automatic base detection (i.e. when base is equal to 0).

It should be positive.

num2

A GMP object, an int, or a string that can be interpreted as a number following the same logic as if the string was used in gmp_init() with automatic base detection (i.e. when base is equal to 0).

It should be positive.

Return Values

The hamming distance between num1 and num2, as an int.

Examples

Example #1 gmp_hamdist() example

<?php $ham1 = gmp_init("1001010011", 2); $ham2 = gmp_init("1011111100", 2); echo gmp_hamdist($ham1, $ham2) . "\n";/* hamdist is equivalent to: */ echo gmp_popcount(gmp_xor($ham1, $ham2)) . "\n"; ?>

The above example will output:

Found A Problem?

Bas Vijfwinkel ¶

7 years ago

For those without gmp support :
 <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>h</mi><mi>a</mi><mi>m</mi><mi>m</mi><mi>i</mi><mi>n</mi><msub><mi>g</mi><mi>d</mi></msub><mi>i</mi><mi>s</mi><mi>t</mi><mi>a</mi><mi>n</mi><mi>c</mi><mi>e</mi><mo>=</mo><mi>c</mi><mi>o</mi><mi>u</mi><mi>n</mi><mi>t</mi><mo stretchy="false">(</mo><mi>a</mi><mi>r</mi><mi>r</mi><mi>a</mi><msub><mi>y</mi><mi>d</mi></msub><mi>i</mi><mi>f</mi><msub><mi>f</mi><mi>a</mi></msub><mi>s</mi><mi>s</mi><mi>o</mi><mi>c</mi><mo stretchy="false">(</mo><mi>s</mi><mi>t</mi><msub><mi>r</mi><mi>s</mi></msub><mi>p</mi><mi>l</mi><mi>i</mi><mi>t</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">hamming_distance = count(array_diff_assoc(str_split(</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord mathnormal">hammin</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.03588em;">g</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3361em;"><span style="top:-2.55em;margin-left:-0.0359em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">d</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal">i</span><span class="mord mathnormal">s</span><span class="mord mathnormal">t</span><span class="mord mathnormal">an</span><span class="mord mathnormal">ce</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">co</span><span class="mord mathnormal">u</span><span class="mord mathnormal">n</span><span class="mord mathnormal">t</span><span class="mopen">(</span><span class="mord mathnormal">a</span><span class="mord mathnormal" style="margin-right:0.02778em;">rr</span><span class="mord mathnormal">a</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.03588em;">y</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3361em;"><span style="top:-2.55em;margin-left:-0.0359em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">d</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal">i</span><span class="mord mathnormal" style="margin-right:0.10764em;">f</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.10764em;">f</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.1514em;"><span style="top:-2.55em;margin-left:-0.1076em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">a</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal">ssoc</span><span class="mopen">(</span><span class="mord mathnormal">s</span><span class="mord mathnormal">t</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.1514em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">s</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal" style="margin-right:0.01968em;">pl</span><span class="mord mathnormal">i</span><span class="mord mathnormal">t</span><span class="mopen">(</span></span></span></span>string1), str_split($string2)));

And if you are not sure if your strings have equal length :
 <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>h</mi><mi>a</mi><mi>m</mi><mi>m</mi><mi>i</mi><mi>n</mi><msub><mi>g</mi><mi>d</mi></msub><mi>i</mi><mi>s</mi><mi>t</mi><mi>a</mi><mi>n</mi><mi>c</mi><mi>e</mi><mo>=</mo><mi>c</mi><mi>o</mi><mi>u</mi><mi>n</mi><mi>t</mi><mo stretchy="false">(</mo><mi>a</mi><mi>r</mi><mi>r</mi><mi>a</mi><msub><mi>y</mi><mi>d</mi></msub><mi>i</mi><mi>f</mi><msub><mi>f</mi><mi>a</mi></msub><mi>s</mi><mi>s</mi><mi>o</mi><mi>c</mi><mo stretchy="false">(</mo><mi>s</mi><mi>t</mi><msub><mi>r</mi><mi>s</mi></msub><mi>p</mi><mi>l</mi><mi>i</mi><mi>t</mi><mo stretchy="false">(</mo><mi>s</mi><mi>t</mi><msub><mi>r</mi><mi>p</mi></msub><mi>a</mi><mi>d</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">hamming_distance = count(array_diff_assoc(str_split(str_pad(</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord mathnormal">hammin</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.03588em;">g</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3361em;"><span style="top:-2.55em;margin-left:-0.0359em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">d</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal">i</span><span class="mord mathnormal">s</span><span class="mord mathnormal">t</span><span class="mord mathnormal">an</span><span class="mord mathnormal">ce</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1.0361em;vertical-align:-0.2861em;"></span><span class="mord mathnormal">co</span><span class="mord mathnormal">u</span><span class="mord mathnormal">n</span><span class="mord mathnormal">t</span><span class="mopen">(</span><span class="mord mathnormal">a</span><span class="mord mathnormal" style="margin-right:0.02778em;">rr</span><span class="mord mathnormal">a</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.03588em;">y</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3361em;"><span style="top:-2.55em;margin-left:-0.0359em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">d</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal">i</span><span class="mord mathnormal" style="margin-right:0.10764em;">f</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.10764em;">f</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.1514em;"><span style="top:-2.55em;margin-left:-0.1076em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">a</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal">ssoc</span><span class="mopen">(</span><span class="mord mathnormal">s</span><span class="mord mathnormal">t</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.1514em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">s</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal" style="margin-right:0.01968em;">pl</span><span class="mord mathnormal">i</span><span class="mord mathnormal">t</span><span class="mopen">(</span><span class="mord mathnormal">s</span><span class="mord mathnormal">t</span><span class="mord"><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.1514em;"><span style="top:-2.55em;margin-left:-0.0278em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">p</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.2861em;"><span></span></span></span></span></span></span><span class="mord mathnormal">a</span><span class="mord mathnormal">d</span><span class="mopen">(</span></span></span></span>string1,strlen($string2)-strlen($string1),' ')), str_split(str_pad($string2,strlen($string1)-strlen($string2),' '))));

grabzila at gmail dot com ¶

4 years ago

<?php
$hamdist = gmp_hamdist(-100, -10); // 4
$hamdist = gmp_hamdist(100, 10);  // 5
?>

The function works great with negative numbers.