How to sort an array of associative arrays by value of a given key in PHP

Question

Given this array    inventory   array      array  type   gt  fruit    price   gt 3 50      array  type   gt  milk    price   gt 2 90      array  type   gt  pork    price   gt 5 43         I would like to sort  inventory s elements by price to get    inventory   array      array  type   gt  pork    price   gt 5 43      array  type   gt  fruit    price   gt 3 50      array  type   gt  milk    price   gt 2 90         How can I do this

User · Answer

Here is a method that I found long ago and cleaned up a bit. This works great, and can be quickly changed to accept objects as well.

/**
 * A method for sorting arrays by a certain key:value.
 * SortByKey is the key you wish to sort by
 * Direction can be ASC or DESC.
 *
 * @param $array
 * @param $sortByKey
 * @param $sortDirection
 * @return array
 */
private function sortArray($array, $sortByKey, $sortDirection) {

    $sortArray = array();
    $tempArray = array();

    foreach ( $array as $key => $value ) {
        $tempArray[] = strtolower( $value[ $sortByKey ] );
    }

    if($sortDirection=='ASC'){ asort($tempArray ); }
        else{ arsort($tempArray ); }

    foreach ( $tempArray as $key => $temp ){
        $sortArray[] = $array[ $key ];
    }

    return $sortArray;

}

to change the method to sort objects simply change the following line:

$tempArray[] = strtolower( $value[ $sortByKey ] ); to $tempArray[] = strtolower( $value->$sortByKey );

To run the method simply do

sortArray($inventory,'price','ASC');

User · Answer

I use uasort like this   lt  php  users                    username    gt   joe            age    gt  11                       username    gt   rakoto            age    gt  21                       username    gt   rabe            age    gt  17                       username    gt   fy            age    gt  19                 uasort  users  function   item   compare        return  item  username    gt    compare  username          var dump  users

User · Answer

PHP 7   As of PHP 7  this can be done concisely using usort with an anonymous function that uses the spaceship operator to compare elements   You can do an ascending sort like this   usort  inventory  function   item1   item2        return  item1  price    lt   gt   item2  price          Or a descending sort like this   usort  inventory  function   item1   item2        return  item2  price    lt   gt   item1  price          To understand how this works  note that usort takes a user-provided comparison function that must behave as follows  from the docs       The comparison function must return an integer less than  equal to  or greater than zero if the first argument is considered to be respectively less than  equal to  or greater than the second    And note also that  lt   gt   the spaceship operator      returns 0 if both operands are equal  1 if the left is greater  and -1 if the right is greater   which is exactly what usort needs  In fact  almost the entire justification given for adding  lt   gt  to the language in https   wiki php net rfc combined-comparison-operator is that it     makes writing ordering callbacks for use with usort   easier     PHP 5 3   PHP 5 3 introduced anonymous functions  but doesn t yet have the spaceship operator  We can still use usort to sort our array  but it s a little more verbose and harder to understand   usort  inventory  function   item1   item2        if   item1  price       item2  price    return 0      return  item1  price    lt   item2  price     -1   1        Note that although it s fairly common for comparators dealing with integer values to just return the difference of the values  like  item2  price   -  item1  price    we can t safely do that in this case  This is because the prices are floating point numbers in the question asker s example  but the comparison function we pass to usort has to return integers for usort to work properly      Returning non-integer values from the comparison function  such as float  will result in an internal cast to integer of the callback s return value  So values such as 0 99 and 0 1 will both be cast to an integer value of 0  which will compare such values as equal    This is an important trap to bear in mind when using usort in PHP 5 x  My original version of this answer made this mistake and yet I accrued ten upvotes over thousands of views apparently without anybody noticing the serious bug  The ease with which lackwits like me can screw up comparator functions is precisely the reason that the easier-to-use spaceship operator was added to the language in PHP 7

User · Answer

try this   asort  array to sort  SORT NUMERIC     for reference see this  http   php net manual en function asort php  see various sort flags here  http   www php net manual en function sort php

User · Answer

Just in one line custom function function cmp  a   b    return  float   a  price    lt   float  b  price       uasort  inventory   cmp    print r  inventory      result  Array    2    gt  Array                type    gt  pork          price    gt  5 43         0    gt  Array                type    gt  fruit          price    gt  3 5         1    gt  Array                type    gt  milk          price    gt  2 9

User · Answer

You can use usort with anonymous function  e g   usort  inventory  function   a   b    return strnatcmp  a  price     b  price

User · Answer

inventory        array array  type   gt  fruit    price   gt 3 50             array  type   gt  milk    price   gt 2 90             array  type   gt  pork    price   gt 5 43                 function pricesort  a   b       a    a  price       b    b  price      if   a     b      return 0    return   a  gt   b    -1   1     usort  inventory   pricesort       uksort  inventory   pricesort     print  first     inventory 0   type     n n       for usort    prints milk  item with lowest price     for uksort    prints fruit  item with key 0 in the original  inventory      foreach prints the same for usort and uksort  foreach  inventory as  i     print  i  type         i  price     n        outputs   first  pork  pork  5 43 fruit  3 5 milk  2 9

User · Answer

You are right  the function you re looking for is array multisort    Here s an example taken straight from the manual and adapted to your case   price   array    foreach   inventory as  key   gt   row         price  key     row  price      array multisort  price  SORT DESC   inventory    As of PHP 5 5 0 you can use array column   instead of that foreach   price   array column  inventory   price     array multisort  price  SORT DESC   inventory

User · Answer

I ended on this   function sort array of array  amp  array   subfield         sortarray   array        foreach   array as  key   gt   row                 sortarray  key     row  subfield              array multisort  sortarray  SORT ASC   array       Just call the function  passing the array and the name of the field of the second level array  Like   sort array of array  inventory   price

User · Answer

Since your array elements are arrays themselves with string keys  your best bet is to define a custom comparison function   It s pretty quick and easy to do   Try this   function invenDescSort  item1  item2        if   item1  price       item2  price    return 0      return   item1  price    lt   item2  price      1   -1    usort  inventory  invenDescSort    print r  inventory     Produces the following   Array        0    gt  Array                        type    gt  pork              price    gt  5 43                 1    gt  Array                        type    gt  fruit              price    gt  3 5                 2    gt  Array                        type    gt  milk              price    gt  2 9

User · Answer

For PHP 7 and later versions          A method for sorting associative arrays by a key and a direction     Direction can be ASC or DESC         param  array     param  key     param  direction     return mixed  array     function sortAssociativeArrayByKey  array   key   direction        switch   direction           case  ASC               usort  array  function   first   second  use   key                    return  first  key   lt   gt   second  key                               break          case  DESC               usort  array  function   first   second  use   key                    return  second  key   lt   gt   first  key                               break          default              break             return  array      Usage    inventory   sortAssociativeArrayByKey  inventory   price    ASC

User · Answer

try this    prices   array column  inventory   price    array multisort  prices  SORT DESC   inventory   print r  inventory

User · Answer

From Sort an array of associative arrays by value of given key in php  by using usort  http   php net usort    we can sort an array in ascending and descending order  just we need to create a function and pass it as parameter in usort  As per below example used greater than for ascending order if we passed less than condition then it s sort in descending order  Example    array   array    array  price   gt  1000 50   product   gt  test1      array  price   gt  8800 50   product   gt  test2      array  price   gt  200 0   product   gt  test3       function cmp  a   b      return  a  price    gt   b  price       usort  array   quot cmp quot    print r  array    Output  Array         0    gt  Array                        price    gt  200 0              product    gt  test3                 1    gt  Array                        price    gt  1000 50              product    gt  test1                 2    gt  Array                        price    gt  8800 50              product    gt  test2

User · Answer

Was tested on 100 000 records  Time in seconds calculated by funciton microtime   Only for unique values on sorting key positions   Solution of function of  Josh Davis  Spended time  1 5768740177155  Mine solution  Spended time  0 094044923782349  Solution   function SortByKeyValue  data   sortKey   sort flags SORT ASC        if  empty  data  or empty  sortKey   return  data        ordered   array        foreach   data as  key   gt   value           ordered  value  sortKey      value       ksort  ordered   sort flags        return array values  ordered       array values   added for identical result with multisort

User · Answer

While others have correctly suggested the use of array multisort    for some reason no answer seems to acknowledge the existence of array column    which can greatly simplify the solution  So my suggestion would be   array multisort array column  inventory   price    SORT DESC   inventory

User · Answer

arr1   array       array  id   gt 1  name   gt  aA   cat   gt  cc        array  id   gt 2  name   gt  aa   cat   gt  dd        array  id   gt 3  name   gt  bb   cat   gt  cc        array  id   gt 4  name   gt  bb   cat   gt  dd        result1   array msort  arr1  array  name   gt SORT DESC     result2   array msort  arr1  array  cat   gt SORT ASC     result3   array msort  arr1  array  name   gt SORT DESC   cat   gt SORT ASC      function array msort  array   cols         colarr   array        foreach   cols as  col   gt   order         colarr  col    array        foreach   array as  k   gt   row     colarr  col       k    strtolower  row  col          eval    array multisort     foreach   cols as  col   gt   order         eval      colarr      col         order          eval   substr  eval 0 -1        eval  eval    ret   array    foreach   colarr as  col   gt   arr        foreach   arr as  k   gt   v             k   substr  k 1           if   isset  ret  k     ret  k     array  k            ret  k   col     array  k   col           return  ret

User · Answer

This function is re-usable   function usortarr  amp  array   key   callback    strnatcasecmp         uasort  array  function  a   b  use  key   callback            return call user func  callback   a  key    b  key                It works well on string values by default  but you ll have to sub the callback for a number comparison function if all your values are numbers

User · Answer

Complete Dynamic Function I jumped here for associative array sorting and found this amazing function on http   php net manual en function sort php  This function is very dynamic that sort in ascending and descending order with specified key   Simple function to sort an array by a specific key  Maintains index association   lt  php  function array sort  array   on   order SORT ASC         new array   array         sortable array   array         if  count  array   gt  0            foreach   array as  k   gt   v                if  is array  v                     foreach   v as  k2   gt   v2                        if   k2     on                             sortable array  k     v2                                                        else                    sortable array  k     v                                   switch   order                case SORT ASC                  asort  sortable array               break              case SORT DESC                  arsort  sortable array               break                     foreach   sortable array as  k   gt   v                 new array  k     array  k                        return  new array      people   array      12345   gt  array           id    gt  12345           first name    gt   Joe            surname    gt   Bloggs            age    gt  23           sex    gt   m             12346   gt  array           id    gt  12346           first name    gt   Adam            surname    gt   Smith            age    gt  18           sex    gt   m             12347   gt  array           id    gt  12347           first name    gt   Amy            surname    gt   Jones            age    gt  21           sex    gt   f            print r array sort  people   age   SORT DESC       Sort by oldest first print r array sort  people   surname   SORT ASC       Sort by surname

User · Answer

You might try to define your own comparison function and then use usort

[php] How to sort an array of associative arrays by value of a given key in PHP?

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