How to search by key value in a multidimensional array in PHP

Question

Is there any fast way to get all subarrays where a key value pair was found in a multidimensional array  I can t say how deep the array will be   Simple example array    arr   array 0   gt  array id  gt 1 name  gt  cat 1                 1   gt  array id  gt 2 name  gt  cat 2                 2   gt  array id  gt 3 name  gt  cat 1        When I search for key name and value  cat 1  the function should return   array 0   gt  array id  gt 1 name  gt  cat 1          1   gt  array id  gt 3 name  gt  cat 1        I guess the function has to be recursive to get down to the deepest level

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http   snipplr com view 51108 nested-array-search-by-value-or-key    lt  php    PHP 5 3  function searchNestedArray array  array   search   mode    value          foreach  new RecursiveIteratorIterator new RecursiveArrayIterator  array   as  key   gt   value            if   search          mode                 return true            return false      data   array      array  abc    ddd         ccc        bbb       array  aaa   array  yyy    mp    gt  555       var dump searchNestedArray  data  555

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If you want to search for array of keys this is good  function searchKeysInMultiDimensionalArray  array   keys         results   array         if  is array  array              resultArray   array intersect key  array  array flip  keys            if   empty  resultArray                  results      resultArray                     foreach   array as  subarray                 results   array merge  results  searchKeysInMultiDimensionalArray  subarray   keys                         return  results      Keys will not overwrite because each set of key    values will be in separate array in resulting array  If you don t want duplicate keys then use this one  function searchKeysInMultiDimensionalArray  array   keys         results   array         if  is array  array              resultArray   array intersect key  array  array flip  keys            if   empty  resultArray                 foreach  resultArray as  key   gt   single                      results  key     single                                   foreach   array as  subarray                 results   array merge  results  searchKeysInMultiDimensionalArray  subarray   keys                         return  results

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if  isset  array  key    amp  amp   array  key      value    A minor imporvement to the fast version

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lt  php  arr   array 0   gt  array  id   gt 1  name   gt  cat 1                 1   gt  array  id   gt 2  name   gt  cat 2                 2   gt  array  id   gt 3  name   gt  cat 1       arr   array filter  arr  function  ar       return   ar  name       cat 1         return   ar  name       cat 1  AND  ar  id       3      you can add multiple conditions      echo   lt pre gt    print r  arr      gt    Ref  http   php net manual en function array-filter php

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Here is solution    lt  php  students  e1003    birthplace       Mandaluyong  lt br gt      students  ter1003    birthplace       San Juan  lt br gt      students  fgg1003    birthplace       Quezon City  lt br gt      students  bdf1003    birthplace       Manila  lt br gt       key   array search  Delata Jona   array column  students   name     echo  key       gt

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Code   function search  array   key   value         results   array         if  is array  array             if  isset  array  key    amp  amp   array  key      value                 results      array                     foreach   array as  subarray                 results   array merge  results  search  subarray   key   value                         return  results      arr   array 0   gt  array id  gt 1 name  gt  cat 1                 1   gt  array id  gt 2 name  gt  cat 2                 2   gt  array id  gt 3 name  gt  cat 1      print r search  arr   name    cat 1       Output   Array        0    gt  Array                        id    gt  1              name    gt  cat 1                 1    gt  Array                        id    gt  3              name    gt  cat 1                If efficiency is important you could write it so all the recursive calls store their results in the same temporary  results array rather than merging arrays together  like so   function search  array   key   value         results   array        search r  array   key   value   results       return  results     function search r  array   key   value   amp  results        if   is array  array             return             if  isset  array  key    amp  amp   array  key      value             results      array             foreach   array as  subarray            search r  subarray   key   value   results             The key there is that search r takes its fourth parameter by reference rather than by value  the ampersand  amp  is crucial   FYI  If you have an older version of PHP then you have to specify the pass-by-reference part in the call to search r rather than in its declaration  That is  the last line becomes search r  subarray   key   value   amp  results

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How about the SPL version instead  It ll save you some typing      I changed your input example to make it harder and    to show it works at lower depths    arr   array 0   gt  array  id   gt 1  name   gt  cat 1                 1   gt  array array  id   gt 3  name   gt  cat 1                  2   gt  array  id   gt 2  name   gt  cat 2         here s the code        arrIt   new RecursiveIteratorIterator new RecursiveArrayIterator  arr      foreach   arrIt as  sub         subArray    arrIt- gt getSubIterator        if   subArray  name        cat 1              outputArray     iterator to array  subArray             What s great is that basically the same code will iterate through a directory for you  by using a RecursiveDirectoryIterator instead of a RecursiveArrayIterator  SPL is the roxor   The only bummer about SPL is that it s badly documented on the web  But several PHP books go into some useful detail  particularly Pro PHP  and you can probably google for more info  too

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Came back to post this update for anyone needing an optimisation tip on these answers  particulary John Kugelman s great answer up above   His posted function work fine but I had to optimize this scenario for handling a 12 000 row resultset  The function was taking an eternal 8 secs to go through all records  waaaaaay too long   I simply needed the function to STOP searching and return when match was found  Ie  if searching for a customer id  we know we only have one in the resultset and once we find the customer id in  the multidimensional array  we want to return   Here is the speed-optimised   and much simplified   version of this function  for anyone in need  Unlike other version  it can only handle only one depth of array  does not recurse and does away with merging multiple results       search array for specific key   value public function searchSubArray Array  array   key   value           foreach   array as  subarray             if  isset  subarray  key    amp  amp   subarray  key      value            return  subarray                    This brought down the the task to match the 12 000 records to a 1 5 secs  Still very costly but much more reasonable

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function in multi array  needle   key   haystack          in multi array   false      if  in array  needle   haystack                  in multi array   true        else               foreach   haystack as  key1   gt   val                       if is array  val                                if  this- gt in multi array  needle   key   val                                         in multi array   true                     break                                                     return  in multi array

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result   array filter  arr  function   var          found   false    array walk recursive  var  function   item   key  use   amp  found           found    found     key     name   amp  amp   item     cat 1           return  found

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I think the easiest way is using php array functions if you know your key  function search array    array   key   value        return array search  value array column  array  key       this return an index that you could find your desired data by this like below   arr   array 0   gt  array  id    gt  1   name    gt   quot cat 1 quot      1   gt  array  id    gt  2   name    gt   quot cat 2 quot      2   gt  array  id    gt  3   name    gt   quot cat 1 quot       echo json encode  arr search array  arr  name   cat 2       this output will    quot id quot  2  quot name quot   quot cat 2 quot

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Be careful of linear search algorithms  the above are linear  in multiple dimensional arrays as they have compounded complexity as its depth increases the number of iterations required to traverse the entire array  Eg   array       0    gt  array   0    gt  something   1    gt  something else                100    gt  array   0    gt  something100   1    gt  something else100       would take at the most 200 iterations to find what you are looking for  if the needle were at  100  1    with a suitable algorithm    Linear algorithms in this case perform at O n   order total number of elements in entire array   this is poor  a million entries  eg a 1000x100x10 array  would take on average 500 000 iterations to find the needle  Also what would happen if you decided to change the structure of your multidimensional array  And PHP would kick out a recursive algorithm if your depth was more than 100  Computer science can do better   Where possible  always use objects instead of multiple dimensional arrays   ArrayObject     MyObject something  something else             MyObject something100  something else100       and apply a custom comparator interface and function to sort and find them   interface Comparable      public function compareTo Comparable  o      class MyObject implements Comparable      public function compareTo Comparable  o                     function myComp Comparable  a  Comparable  b       return  a- gt compareTo  b       You can use uasort   to utilize a custom comparator  if you re feeling adventurous you should implement your own collections for your objects that can sort and manage them  I always extend ArrayObject to include a search function at the very least      arrayObj- gt uasort  myComp      Once they are sorted  uasort is O n log n   which is as good as it gets over arbitrary data   binary search can do the operation in O log n  time  ie a million entries only takes  20 iterations to search  As far as I am aware custom comparator binary search is not implemented in PHP  array search   uses natural ordering which works on object references not their properties   you would have to implement this your self like I do   This approach is more efficient  there is no longer a depth  and more importantly universal  assuming you enforce comparability using interfaces  since objects define how they are sorted  so you can recycle the code infinitely  Much better

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And another version that returns the key value from the array element in which the value is found  no recursion  optimized for speed        if the array is   arr  apples     array  id    gt  1    arr  oranges     array  id    gt  2      then  print r search array  arr   id   2      returns Array    oranges    gt  Array    id    gt  2         instead of Array    0    gt  Array    id    gt  2         search array for specific key   value function search array  array   key   value       return   array         foreach   array as  k  gt  subarray         if  isset  subarray  key    amp  amp   subarray  key      value           return  k     subarray        return  return                 Thanks to all who posted here

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function findKey  tab   key       foreach  tab as  k   gt   value            if  k   key  return  value           if is array  value                  find   findKey  value   key               if  find  return  find                      return null

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I needed something similar  but to search for multidimensional array by value    I took John example and wrote  function  search array by value  array   value             results   array            if  is array  array                  found   array search  value  array               if   found                     results      found                            foreach   array as  subarray                   results   array merge  results   this- gt  search array by value  subarray   value                      return  results          I hope it helps somebody

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This is a revised function from the one that John K  posted    I need to grab only the specific key in the array and nothing above it   function search array    array   key   value          results   array         if   is array  array                  if    array  key      value                          results      array            else               foreach   array as  subarray                    results   array merge   results   this- gt search array  subarray   key   value                          return  results      arr   array 0   gt  array id  gt 1 name  gt  cat 1           1   gt  array id  gt 2 name  gt  cat 2           2   gt  array id  gt 3 name  gt  cat 1      print r search array  arr   name    cat 1

[php] How to search by key=>value in a multidimensional array in PHP

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