array_count_values

(PHP 4, PHP 5, PHP 7)

array_count_values — 统计数组中所有的值出现的次数

说明

array array_count_values ( array $input )

array_count_values() 返回一个数组，该数组用 input 数组中的值作为键名，该值在 input 数组中出现的次数作为值。

参数

input: 统计这个数组的值

返回值

返回一个关联数组，用 input 数组中的值作为键名，该值在数组中出现的次数作为值。

错误／异常

对数组里面的每个不是 string 和 integer 类型的元素抛出一个警告错误（ E_WARNING ）。

范例

Example #1 array_count_values() 例子

  <?php
$array  = array( 1 ,  "hello" ,  1 ,  "world" ,  "hello" );
 print_r ( array_count_values ( $array ));
 ?>

以上例程会输出：

Array
(
    [1] => 2
    [hello] => 2
    [world] => 1
)

参见

count() - 计算数组中的单元数目或对象中的属性个数
array_unique() - 移除数组中重复的值
array_values() - 返回数组中所有的值
count_chars() - 返回字符串所用字符的信息

用户评论:

[#1] jakubplus at gmail dot com [2014-04-07 11:36:17]

In order to apply array_map with callback checking for localised values like city name, country name, you have to provide some sort of comparison array.

Here's an example of array_count_values for Polish city names. Just switch array_keys / array_values in order to obtain lowercase / uppercase.

$arr = array('Warsaw', 'Warsaw', 'Wroc?aw', 'Pozna??', 'Krak?w', 'waRsaw', 'Gda??sk', 'pozna??', 'WROC?AW', 'krak??w', 'GDA?SK');
$lowertoupperpolish = array(
    '?' => '?',
    '?' => '?',
    '?' => '?',
    '?' => '?',
    '??' => '?',
    '??' => '?',
    '?' => '?',
    '?' => '?',
    '?' => '?',
);
function lowers($n) {
    global $lowertoupperpolish;
    return strtolower(str_replace(array_values($lowertoupperpolish), array_keys($lowertoupperpolish), $n));
}
$result = array_count_values(array_map('lowers', $arr));

print_r($result); ...prints:

Array ( [warsaw] => 3 [wroc?aw] => 2 [pozna??] => 2 [krak??w] => 2 [gda??sk] => 2 )

[#2] Dominic Vonk [2013-12-13 16:11:01]

The case-insensitive version:

<?php function array_count_values_ci($array) { $newArray = array(); foreach ($array as $values) { if (!array_key_exists(strtolower($values), $newArray)) { $newArray[strtolower($values)] = 0; } $newArray[strtolower($values)] += 1; } return $newArray; } ?>

[#3] szczepan.krolgmail.c0m [2010-01-17 11:21:19]

Here is a Version with one or more arrays, which have similar values in it:
Use $lower=true/false to ignore/set case Sensitiv.

<?php $ar1[] = array("red","green","yellow","blue"); $ar1[] = array("green","yellow","brown","red","white","yellow"); $ar1[] = array("red","green","brown","blue","black","yellow"); #$ar1= array("red","green","brown","blue","black","red","green"); // Possible with one or multiple Array $res = array_icount_values ($ar1); print_r($res); function array_icount_values($arr,$lower=true) { $arr2=array(); if(!is_array($arr['0'])){$arr=array($arr);} foreach($arr as $k=> $v){ foreach($v as $v2){ if($lower==true) {$v2=strtolower($v2);} if(!isset($arr2[$v2])){ $arr2[$v2]=1; }else{ $arr2[$v2]++; } } } return $arr2; } ?>

[#4] bluej100@gmail [2008-03-25 13:37:13]

byron at byronrode dot co dot za, here are some benchmarks.

<?php $haystack = Array(); for ($i = 0; $i < 1000000; $i++) { $haystack[] = rand(1, 2000); } $needle = rand(1, 2000); echo "__array_count_values()__\n"; $start = microtime(true); $startmem = memory_get_usage(); $counts = array_count_values($haystack); $mem = memory_get_usage()-$startmem; echo 'Count:'.$counts[$needle]."\n"; echo 'Time:'.(microtime(true) - $start)."\n"; echo 'Memory:'.$mem."\n\n"; echo "__array_keys()__\n"; $start = microtime(true); $startmem = memory_get_usage(); $keys = array_keys($haystack, $needle); $mem = memory_get_usage()-$startmem; echo 'Count:'.count($keys)."\n"; echo 'Time:'.(microtime(true) - $start)."\n"; echo 'Memory:'.$mem."\n\n"; echo '__$needle_array[]__'."\n"; $start = microtime(true); $startmem = memory_get_usage(); $x = count($haystack); for($i = 0; $i < $x; $i++){ if($haystack[$i] == $needle){ $needle_array[] = $haystack[$i]; } } $mem = memory_get_usage()-$startmem; $number_of_instances = count($needle_array); echo 'Count:'.$number_of_instances."\n"; echo 'Time:'.(microtime(true) - $start)."\n"; echo 'Memory:'.$mem."\n\n"; echo '__$number_of_instances++__'."\n"; $start = microtime(true); $startmem = memory_get_usage(); $x = count($haystack); $number_of_instances = 0; for($i = 0; $i < $x; $i++){ if($haystack[$i] == $needle){ $number_of_instances++; } } $mem = memory_get_usage()-$startmem; echo 'Count:'.$number_of_instances."\n"; echo 'Time:'.(microtime(true) - $start)."\n"; echo 'Memory:'.$mem."\n\n"; ?>

[www]mytemp$ php array_count_test.php
__array_count_values()__
Count:515
Time:0.0607650279999
Memory:120328

__array_keys()__
Count:515
Time:0.0869138240814
Memory:33016

__$needle_array[]__
Count:515
Time:0.259949922562
Memory:24792

__$number_of_instances++__
Count:515
Time:0.258481025696
Memory:0

However, when you use an array of strings by calling md5(rand(1, 2000)), the performance boosts become less significant:

__array_count_values()__
Count:499
Time:0.491794109344
Memory:184328

__array_keys()__
Count:499
Time:0.36399102211
Memory:30072

__$needle_array[]__
Count:499
Time:0.568728923798
Memory:22104

__$number_of_instances++__
Count:499
Time:0.574353933334
Memory:0

Results are similar for string->string haystacks with foreach traversal.

[#5] Hayley Watson [2008-03-13 11:37:16]

Yet Another case-insensitive version of array_count_values()

<?php $ar = array('J. Karjalainen', 'J. Karjalainen', 60, '60', 'J. Karjalainen', 'j. karjalainen', 'Fastway', 'FASTWAY', 'Fastway', 'fastway', 'YUP'); $ar = array_count_values(array_map('strtolower', $ar)); ?>

[#6] majerm at gmail dot com [2007-06-18 07:50:30]

<?php function array_icount_values($array) {     $ret_array = array();     foreach($array as $value) $ret_array[strtolower($value)]++;     return $ret_array; } $ar = array('J. Karjalainen', 'J. Karjalainen', 60, '60', 'J. Karjalainen', 'j. karjalainen', 'Fastway', 'FASTWAY', 'Fastway', 'fastway', 'YUP'); $ar = array_icount_values($ar); ?>

this prints:

Array
(
    [j. karjalainen] => 4
    [60] => 2
    [fastway] => 4
    [yup] => 1
)

[#7] rabies dot dostojevski at gmail dot com [2007-02-21 01:40:15]

I couldn't find a function for counting the values with case-insensitive matching, so I wrote a quick and dirty solution myself:

<pre><?php function array_icount_values($array) {     $ret_array = array();     foreach($array as $value) {         foreach($ret_array as $key2 => $value2) {             if(strtolower($key2) == strtolower($value)) {                 $ret_array[$key2]++;                 continue 2;             }         }         $ret_array[$value] = 1;     }     return $ret_array; } $ar = array('J. Karjalainen', 'J. Karjalainen', 60, '60', 'J. Karjalainen', 'j. karjalainen', 'Fastway', 'FASTWAY', 'Fastway', 'fastway', 'YUP'); $ar2 = array_count_values($ar); // Normal matching $ar = array_icount_values($ar); // Case-insensitive matching print_r($ar2); print_r($ar); ?></pre>

This prints:

Array
(
    [J. Karjalainen] => 3
    [60] => 2
    [j. karjalainen] => 1
    [Fastway] => 2
    [FASTWAY] => 1
    [fastway] => 1
    [YUP] => 1
)
Array
(
    [J. Karjalainen] => 4
    [60] => 2
    [Fastway] => 4
    [YUP] => 1
)

I don't know how efficient it is, but it seems to work. Needed this function in one of my scripts and thought I would share it.

[#8] coda at bobandgeorge dot com [2005-10-14 05:52:25]

alwaysdrunk's comment only works if you can trust the client web browser. Using this function doesn't validate that every necessary field exists -- only that every field that was submitted has a value in it. Thus if an attacker wished to force a null value into one of the fields, he could (rather easily) construct a modified form without the field and submit THAT.

Besides, you really ought to be validating each field anyway if you're taking user input.

[#9] [Mr.A] [2005-03-06 02:59:17]

I find a very simple solution to count values in multidimentional arrays (example for 2 levels) :

foreach ($array as $a) {
  foreach ($a as $b) {
    $count_values[$b]++;
  }
}

[#10] pmarcIatIgeneticsImedIharvardIedu [2003-01-29 17:42:45]

array_count_values function does not work on multidimentional arrays.
If $score[][] is a bidimentional array, the command
"array_count_values ($score)" return the error message "Warning: Can only count STRING and INTEGER values!".

[#11] manuzhai (AT) php (DOT) net [2002-11-16 06:45:56]

You might use serialize() to serialize your objects before analyzing their frequency. :)