I have the following array:
$name_arr = array('raj','raj','ganesh','rahul','ganesh','mayur','raj','rahul');
I want to sort it like this:
$final_arr = array('raj','raj','raj','ganesh','ganesh','rahul','rahul','mayur');
How can I achieve it?
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4 Answers
Simple way using array_count_values and arsort:-
$array = array_count_values($name_arr); //get all occurrences of each values
arsort($array);
print_r($array);//print occurrences array
$final_array = array();
foreach($array as $key=>$val){ // iterate over occurrences array
for($i=0;$i<$val;$i++){ //apply loop based on occurrences number
$final_array[] = $key; // assign same name to the final array
}
}
print_r($final_array); // print final array
Output:- https://eval.in/847428
answered Aug 19, 2017 at 8:44
Death-is-the-real-truth
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1 Comment
localheinz
This is computationally expensive - there are simpler solutions for this problem.
simple use array_count_values and array_fill and array_merge
1st : array_count_values will get the values presented count as a array like below .
Array ( [raj] => 3 [ganesh] => 2 [rahul] => 2 [mayur] => 1 )
2nd : Apply arsort() . descending order, according to the value
3rd : Loop that array and make the new array based on count fill the array using array_fill .
4th : Then merge the array .
<?php
$name_arr = array('raj','raj','ganesh','rahul','ganesh','mayur','raj','rahul');
$new_arr = array_count_values($name_arr);
arsort($new_arr);
$value=array();
foreach($new_arr as $key=>$val){
$value= array_merge($value,array_fill(0,$val,$key));
}
print_r($value);
?>
4 Comments
localheinz
This is computationally expensive - there are simpler solutions for this problem.
localheinz
With n being the size of the array, you are invoking
array_merge() and array_fill() n times.localheinz
No, but it's just not the best solution.
JYoThI
it's not best solution as well as it's not wrong solution . @localheinz
The easiest way to solve this is by using the built-in functions array_count_values() and usort():
<?php
$name_arr = array('raj','raj','ganesh','rahul','ganesh','mayur','raj','rahul');
$valueCount = array_count_values($name_arr);
$final_arr = $name_arr;
usort($final_arr, function ($a, $b) use ($valueCount) {
return $valueCount[$b] - $valueCount[$a];
});
var_dump($final_arr);
For reference, see:
- http://php.net/manual/en/function.usort.php
- http://php.net/manual/en/function.array-count-values.php
For an example, see:
4 Comments
deceze
Since you keep insisting that rebuilding the array is more expensive… not sure repeated invocation of the comparator function is any cheaper.
localheinz
Even so, it's still the least amount of code while maintaining a high level of legibility, don't you think, @deceze?
deceze
I certainly agree there, and for small arrays this is preferable regardless of its performance, since it's likely fast enough.
HynekS
The code does not seem to work properly – the
$final_arr is not actually sorted by the number of occurrences.<?php
$name_arr = array('raj','raj','ganesh','rahul','ganesh','mayur','raj','rahul');
rsort($name_arr);
print_r($name_arr);
Output
Array (raj , raj , raj , rahul , rahul, mayur, ganesh, ganesh )
1 Comment
localheinz
This might work with this particular array, but it doesn't generically solve the problem stated by the original poster. See php.net/manual/de/function.rsort.php.