array_combine
This doesn't seem to be documented, but it appears that array_count_values will write its key values *back* to corresponding values in the argument array.
For example, say I have an array $id_numbers, consisting of 7 digits which contain leading zeros (so number 1 would be 0000001 and so on). Most probably already know that array_count_values will (lamely, IMO) strip the leading zeros and return the key as a number.
So if
<?php
$id_numbers[0] = 0056789;
$id_numbers[1] = 0012345;
$id_numbers[2] = 0012345;
// then
$id_counts = array_count_values($id_numbers); // will yield
$id_counts[56789] = 1;
$id_counts[12345] = 2;
/* That's not the weird part yet. If you dump $id_numbers you get an interesting result: */
$id_numbers[0] = 56789;
$id_numbers[1] = 12345;
$id_numbers[2] = 12345;
?>
Obviously quite nasty, if you aren't careful.
The way to prevent this is to encapsulate the argument array in the array_values() function:
$id_counts = array_count_values(array_values($id_numbers))
You'll still have the nagging problem that your $id_counts keys are still technically incorrect, but depending on your program or incoming data, a sprintf() should rectify the stripping of zeros (i.e. you basically have to make the array_count_values result a "temporary" array, then loop through that, restore the zeros and populate a new "real" array with correct keys)
array_count_values
(PHP 4, PHP 5)
array_count_values — Compte le nombre de valeurs d'un tableau
Description
array array_count_values
( array $input
)
Retourne un tableau contenant les valeurs du tableau input comme clés et leur fréquence comme valeurs.
Liste de paramètres
- input
-
Le tableau de valeurs à compter
Valeurs de retour
Retourne un tableau associatif de valeurs ayant dont les clés correspondent à input et leurs nombres comme valeurs.
Erreurs / Exceptions
Lance une alerte de niveau E_WARNING pour chaque élément qui n'est pas une chaîne de caractères ou un entier.
Exemples
Exemple #1 Exemple avec array_count_values()
<?php
$array = array(1, "hello", 1, "world", "hello");
print_r(array_count_values($array));
?>
L'exemple ci-dessus va afficher :
Array ( [1] => 2 [hello] => 2 [world] => 1 )
add a note
User Contributed Notesarray_count_values
psbauman
18-Dec-2008 10:48
18-Dec-2008 10:48
bluej100@gmail
25-Mar-2008 10:37
25-Mar-2008 10:37
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.
Hayley Watson
13-Mar-2008 08:37
13-Mar-2008 08:37
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));
?>
byron at byronrode dot co dot za
26-Jun-2007 02:19
26-Jun-2007 02:19
I am building a script for a quiz, and could not find any answers to count the number of times a value was repeated in an array, and came up with the following function.
<?php
// Answers Array
$array = array('a', 'b', 'a', 'a', 'c', 'a', 'd', 'a', 'c', 'd');
// Start Count Function
function count_repeat_values($needle, $haystack){
$x = count($haystack);
for($i = 0; $i < $x; $i++){
if($haystack[$i] == $needle){
$needle_array[] = $haystack[$i];
}
}
$number_of_instances = count($needle_array);
return $number_of_instances;
}
echo count_repeat_values('a', $array);
// will return the value 5
?>
But after writing the function, I happened to stroll upon array_count_values() which I had completely forgotten about.
I know that i could get the value by doing this:
<?php
$array = array('a', 'b', 'a', 'a', 'c', 'a', 'd', 'a', 'c', 'd');
$answer = array_count_values($array);
echo $answer['a']
?>
Would be interesting to see which version works quicker...
majerm at gmail dot com
18-Jun-2007 04:50
18-Jun-2007 04:50
<?
function array_icount_values($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
)
rabies dot dostojevski at gmail dot com
21-Feb-2007 10:40
21-Feb-2007 10:40
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.
meyermagic at gmail dot com
17-Jan-2007 03:43
17-Jan-2007 03:43
Scratch that, I did something stupid. Here is a better function.
<?php
function array_enumerate_keys($array)
{
$index = 0;
$enumerated = array();
$values = array_values($array);
$keys = array_keys($array);
for($index = 0; $index < count($array); $index++)
{
$iteration;
for($iteration = 0; $iteration < $values[$index]; $iteration++)
{
$enumerated = array_merge($enumerated, array($keys[$index]));
}
}
return $enumerated;
}
?>
meyermagic at gmail dot com
16-Jan-2007 11:58
16-Jan-2007 11:58
A possible inverse function for array_count_values
<?php
function array_enumerate_keys($array)
{
$index;
$enumerated;
$values = array_values($array);
$keys = array_keys($array);
for($index = 0; $index < count($array); $index++)
{
$iteration;
for($iteration = 0; $iteration < $values[$index]; $iteration++)
{
$enumerated .= $keys[$index] . ',';
}
}
return explode(',', $enumerated);
}
?>
coda at bobandgeorge dot com
14-Oct-2005 02:52
14-Oct-2005 02:52
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.
alwaysdrunk at gmail com
12-May-2005 09:14
12-May-2005 09:14
if you have too many values in $_POST,$_GET array that needs to be controlled with isset() in oreder to understand the form is filled completely and have no empty text boxes.
you can try this,it saves time.
<?
$n = array_count_values($_POST);
if (!isset($n[''])) {
echo "The form is filled completely";
}
else
{ die("Please fill the form comlpetely"); }
//tested in php 5
?>
[Mr.A]
06-Mar-2005 11:59
06-Mar-2005 11:59
I find a very simple solution to count values in multidimentional arrays (example for 2 levels) :
foreach ($array as $a) {
foreach ($a as $b) {
$count_values[$b]++;
}
}
blauauge at figh7club dot com
04-Sep-2003 06:12
04-Sep-2003 06:12
my solution for count on multidimentional arrays.
<?php
for($i = 0; $i < count($array); $i++) {
$detail = explode("|", $array[$i]);
echo "$i - $detail[0] - $detail[1]<br><br>";
if($detail[1] == '1') { $wieoft1 = $wieoft1 +=1; }
if($detail[1] == '2') { $wieoft2 = $wieoft2 +=1; }
if($detail[1] == '3') { $wieoft3 = $wieoft3 +=1; }
}
echo ". $wieoft1 : $wieoft2 : $wieoft3";
?>
looks not pretty fine yet works great for me.
make it bigger for your own.
programmer at bardware dot de
19-Aug-2003 08:24
19-Aug-2003 08:24
array_count_values returns the number of keys if empty(value). I expected array_count_values to return 0 for empty values.
Array looks like:
Array
(
[459] =>
[543] =>
[8959] =>
[11273] =>
)
array_count_values returns:
Array
(
[] => 4
)
count(array_count_values(array)) does thus not report there are no values (other than empty) in the array.
I therefore check:
$arrFoo=array_count_values($arrBar);
if(isset($arrFoo[""]) $allempty=count($arrBar)==$arrFoo[""];
if(!$allempty)
//process the array
else
//no need to work on the array
digleu at codeway dot de
28-May-2003 11:58
28-May-2003 11:58
I fount a solution for the count of array elements in the sense of array_count_values, but i was not able to use the function array_count_values itself because it does not say me if arrays exists in the given array, so i had to use a foreach loop and a little bit of recursivity ;)
<?php
function array_count_values_multidim($a,$out=false) {
if ($out===false) $out=array();
if (is_array($a)) {
foreach($a as $e)
$out=array_count_values_multidim($e,$out);
}
else {
if (array_key_exists($a,$out))
$out[$a]++;
else
$out[$a]=1;
}
return $out;
}
?>
pmarcIatIgeneticsImedIharvardIedu
30-Jan-2003 02:42
30-Jan-2003 02:42
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!".
manuzhai (AT) php (DOT) net
16-Nov-2002 03:45
16-Nov-2002 03:45
You might use serialize() to serialize your objects before analyzing their frequency. :)
jon at fuck dot org
14-Aug-2002 11:31
14-Aug-2002 11:31
suggested plan of attack:
<pre>
<?
class MyObject {
function MyObject($t = 'none')
{
$this->$myTag = $t;
}
}
$myArray = array();
for ($i = 1 ; $i < 11 ; $i++)
{
$myobj = new MyObject( str_pad('n', $i, 'x') );
$myArray[ $myobj->$myTag ] = $myobj;
}
print_r( array_count_values(array_keys($myArray)) );
?>
to sum up:
assuming each instance of an object you create has some sort of tag, e.g.,
$this->$myTag=get_class($this)
..you should be set. objects dont have value to compare the way strings and integers do, so, $myTag's value is arbitrary.
tschneider at formel4 dot de
12-Jun-2002 04:09
12-Jun-2002 04:09
This does not works with objects. If you have an array filled with objects, you can not count them.
Example:
<?php
$myArray = array();
for ($i = 0 ; $i < 10 ; $i++)
{
$myObject = new MyObject();
$myArray[$i] = $myObject;
}
echo (array_count_values($myArray));
?>
This gives you:
Warning: Can only count STRING and INTEGER values...
Found no solution for this yet...