How to flatten a multi-dimensional array to simple one in PHP

Question

It s probably beginner question but I m going through documentation for longer time already and I can t find any solution  I thought I could use implode for each dimension and then put those strings back together with str split to make new simple array  However I never know if the join pattern isn t also in values and so after doing str split my original values could break   Is there something like combine  array1   array2  for arrays inside of multi-dimensional array

User · Answer

array   your multidimensional array   flat array   array     foreach new RecursiveIteratorIterator new RecursiveArrayIterator  array   as  k  gt  v     flat array  k     v       Also documented  http   www phpro org examples Flatten-Array html

User · Answer

array    your array   result   call user func array  array merge    array    echo   lt pre gt    print r  result     REF  http   php net manual en function call-user-func-array php  Here is another solution  works with multi-dimensional array     function array flatten  array         return   array       foreach   array as  key   gt   value           if  is array  value     return   array merge  return  array flatten  value            else   return  key     value           return  return       array    Your array   result   array flatten  array    echo   lt pre gt    print r  result

User · Answer

Another method from PHP s user comments  simplified  and here   function array flatten recursive  array        if    array  return false      flat   array        RII   new RecursiveIteratorIterator new RecursiveArrayIterator  array       foreach   RII as  value   flat      value     return  flat      The big benefit of this method is that it tracks the depth of the recursion  should you need that while flattening  This will output    array   array        A    gt  array  B    gt  array  1  2  3          C    gt  array 4  5       print r array flatten recursive  array       Returns   Array         0    gt  1       1    gt  2       2    gt  3       3    gt  4       4    gt  5

User · Answer

This is a one line  SUPER easy to use    result   array    array walk recursive  original array function  v  use   amp  result    result      v        It is very easy to understand  inside the anonymous function closure   v is the value of your  original array

User · Answer

Simple approach  See it via recursion     lt  php  function flatten array  simple   static  outputs array    foreach    simple as  value    if is array  value        flatten array  value     else       outputs    value       return  outputs      eg   s   gt   p   n   gt   t       out flatten array  eg   print r  out      gt

User · Answer

If you re okay with loosing array keys  you may flatten a multi-dimensional array using a recursive closure as a callback that utilizes array values    making sure that this callback is a parameter for array walk    as follows    lt  php     array    1 2 3  5 6 7     nu array   null   callback   function    item   use  amp  callback   amp  nu array        if   is array  item          nu array      item            else     if   is array   item            foreach  array values  item  as  v             if     is array  v                    nu array      v                      else                           callback   v             continue                                  array walk  array   callback   print r  nu array     The one drawback of the preceding example is that it involves writing far more code than the following solution which uses array walk recursive   along with a simplified callback    lt  php     array    1 2 3  5 6 7      nu array       array walk recursive  array  function    item   use  amp  nu array                                                    nu array      item                            print r  nu array     See live code  This example seems preferable to the previous one  hiding the details about how values are extracted from a multidimensional array  Surely  iteration occurs  but whether it entails recursion or control structure s   you ll only know from perusing array c  Since functional programming focuses on input and output rather than the minutiae of obtaining a result  surely one can remain unconcerned about how behind-the-scenes iteration occurs  that is until a perspective employer poses such a question

User · Answer

A new approach based on the previous example function submited by chaos  which fixes the bug of overwritting string keys in multiarrays     Flatten a multidimensional array to one dimension  optionally preserving keys     array - the array to flatten    preserve keys - 0  default  to not preserve keys  1 to preserve string keys only  2 to preserve all keys    out - internal use argument for recursion  function flatten array  array   preserve keys   2   amp  out   array     amp  last subarray found             foreach  array as  key   gt   child                        if is array  child                                  last subarray found    key                   out   flatten array  child   preserve keys   out   last subarray found                             elseif  preserve keys   is string  key   gt  1                                if   last subarray found                                         sfinal key value    last subarray found          key                                    else                                        sfinal key value    key                                     out  sfinal key value     child                            else                                out      child                                   return  out     Example   newarraytest   array     last subarray found        this- gt flatten array  array  2   newarraytest   last subarray found

User · Answer

You can use the flatten function from Non-standard PHP library  NSPL   It works with arrays and any iterable data structures   assert  1  2  3  4  5  6  7  8  9      flatten   1   2   3        4  5  6     7  8   9

User · Answer

If you re interested in just the values for one particular key  you might find this approach useful   function valuelist  array   array column         return   array        foreach  array AS  row            return    row  array column              return  return       Example   Given  get role action   array 3       0   gt    array 2          ACTION CD    gt      string 12   ADD DOCUMENT        ACTION REASON    gt      NULL        1   gt    array 2          ACTION CD    gt      string 13   LINK DOCUMENT        ACTION REASON    gt      NULL        2   gt    array 2          ACTION CD    gt      string 15   UNLINK DOCUMENT        ACTION REASON    gt      NULL         than  variables  role action list   valuelist  get role action   ACTION CD    would result in    variables  role action list    gt    array 3         0   gt      string 12   ADD DOCUMENT       1   gt      string 13   LINK DOCUMENT       2   gt      string 15   UNLINK DOCUMENT        From there you can perform value look-ups like so   if  in array  ADD DOCUMENT    variables  role action list             do something

User · Answer

Using higher-order functions  note  I m using inline anonymous functions  which appeared in PHP 5 3     function array flatten  array        return array reduce           array          function  prev   element                if   is array  element                    prev      element              else                  prev   array merge  prev  array flatten  element                return  prev                     array

User · Answer

you can try this   function flat an array  a        foreach  a as  i                if is array  i                          if  na   na   array merge  na flat an array  i                else  na   flat an array  i                     else  na      i            return  na

User · Answer

Sorry for necrobumping  but none of the provided answers did what I intuitively understood as  quot flattening a multidimensional array quot   Namely this case       a    gt         b    gt   value          all of the provided solutions would flatten it into just   value    but that loses information about the key and the depth  plus if you have another  b  key somewhere else  it will overwrite them  I wanted to get a result like this       a b    gt   value      array walk recursive doesn t pass the information about the key it s currently recursing  so I did it with just plain recursion  function flatten  array   prefix              return           foreach   array as  key   gt   value            if  is array  value                  return   array merge  return  flatten  value   prefix    key                    else                return  prefix    key     value                      return  return     Modify the  prefix and     separator to your liking  Playground here  https   3v4l org 0B8hf

User · Answer

I found a simple way to convert multilevel array into one  I use the function  http build query  which converts the array into a url string  Then  split the string with explode and decode the value   Here is a sample    converted   http build query  data    rows   explode   amp     converted    output   array    foreach  rows AS  k   gt   v      list  kk   vv    explode       v       output  urldecode  kk       urldecode  vv     return  output

User · Answer

With PHP 7  you can use generators and generator delegation  yield from  to flatten an array   function array flatten iterator  array  array        foreach   array as  value            if  is array  value                 yield from array flatten iterator  value             else               yield  value                     function array flatten  array  array        return iterator to array array flatten iterator  array   false       Example    array         1      2                3          4          5                        6              7                    8          9             10      11          var dump array flatten  array      http   3v4l org RU30W

User · Answer

function flatten array  array   preserve keys   0   amp  out   array            Flatten a multidimensional array to one dimension  optionally preserving keys               array - the array to flatten        preserve keys - 0  default  to not preserve keys  1 to preserve string keys only  2 to preserve all keys        out - internal use argument for recursion     foreach  array as  key   gt   child          if is array  child                out   flatten array  child   preserve keys   out           elseif  preserve keys   is string  key   gt  1               out  key     child          else              out      child      return  out

User · Answer

any of this didnt work for me      so had to run it myself   works just fine   function arrayFlat  arr    out           foreach  arr as  key   gt   value            if  is array  value                 out     value               else               out     key                   out    arrayFlat  value                        return trim  out            result   explode     arrayFlat  yourArray    echo   lt pre gt    print r  result   echo   lt  pre gt

User · Answer

A non-recursive solution  but order-destroying    function flatten  ar         toflat   array  ar        res   array         while    r   array shift  toflat       NULL            foreach   r as  v                if  is array  v                      toflat      v                else                    res      v                                     return  res

User · Answer

Use array walk recursive   lt  php   aNonFlat   array      1      2      array          3          4          5          array              6              7                    8          9             10      11      objTmp    object  array  aFlat    gt  array      array walk recursive  aNonFlat  create function   amp  v   k   amp  t     t- gt aFlat      v      objTmp    var dump  objTmp- gt aFlat       array 11       0   gt    int 1     1   gt    int 2     2   gt    int 3     3   gt    int 4     4   gt    int 5     5   gt    int 6     6   gt    int 7     7   gt    int 8     8   gt    int 9     9   gt    int 10     10   gt    int 11          gt    Tested with PHP 5 5 9-1ubuntu4 24  cli   built  Mar 16 2018 12 32 06

User · Answer

consider  mArray as multidimensional array and  sArray as single dimensional array this code will ignore the parent array     function flatten array2  mArray         sArray   array         foreach   mArray as  row            if     is array  row                   if  sArray      row                           else                sArray   array merge  sArray flatten array2  row                        return  sArray

User · Answer

In PHP  5 3 and based on Luc M s answer  the first one  you can make use of closures like this  array walk recursive  aNonFlat  function  amp  v   k   amp  t   t- gt aFlat      v     objTmp     I love this because I don t have to surround the function s code with quotes like when using create function

User · Answer

If you specifically have an array of arrays that doesn t go further than one level deep  a use case I find common  you can get away with array merge and the splat operator    lt  php   notFlat     1 2   3 4     flat   array merge     notFlat   var dump  flat     Output   array 4       0   gt    int 1     1   gt    int 2     2   gt    int 3     3   gt    int 4      The splat operator effectively changes the array of arrays to a list of arrays as arguments for array merge

User · Answer

Someone might find this useful  I had a problem flattening array at some dimension  I would call it last dimension so for example  if I have array like   array      germany    gt     array        cars    gt       array          bmw    gt         array           0   gt   m4           1   gt   x3           2   gt   x8                           france    gt     array        cars    gt       array          peugeot    gt         array           0   gt   206           1   gt   3008           2   gt   5008                            Or   array      earth    gt     array        germany    gt       array          cars    gt         array            bmw    gt           array             0   gt   m4             1   gt   x3             2   gt   x8                                      mars    gt     array        france    gt       array          cars    gt         array            peugeot    gt           array             0   gt   206             1   gt   3008             2   gt   5008                                       For both of these arrays when I call method below I get result   array     0   gt     array       0   gt   m4       1   gt   x3       2   gt   x8          1   gt     array       0   gt   206       1   gt   3008       2   gt   5008            So I am flattening to last array dimension which should stay the same  method below could be refactored to actually stop at any kind of level   function flattenAggregatedArray  aggregatedArray         final    lvls            counter   1       lvls  counter     aggregatedArray         elem   current  aggregatedArray        while   elem           while is array  elem                 counter                 lvls  counter     elem               elem    current  elem                       final      lvls  counter            elem   next  lvls -- counter            while    elem     null               if  isset  lvls  counter-1                      elem   next  lvls -- counter                              else                  return  final

User · Answer

Given multi-dimensional array and converting it into one-dimensional  can be done by unsetting all values which are having arrays and saving them into first dimension  for example   function  flatten array  arr      while   arr        list  key   value    each  arr        is array  value     arr    value    out  key     value      unset  arr  key          return  array  out

[php] How to "flatten" a multi-dimensional array to simple one in PHP?

Examples related to php

Examples related to arrays

Examples related to multidimensional-array