How to insert element into arrays at specific position

Question

Let s imagine that we have two arrays    array 1   array     0    gt   zero      1    gt   one      2    gt   two      3    gt   three        array 2   array     zero     gt   0      one      gt   1      two      gt   2      three    gt   3        Now  I d like to insert array  sample key    gt   sample value   after third element of each array  How can I do it

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For your first array  use array splice      array 1   array     0    gt   zero      1    gt   one      2    gt   two      3    gt   three       array splice  array 1  3  0   more    print r  array 1     output   Array       0    gt  zero      1    gt  one      2    gt  two      3    gt  more      4    gt  three     for the second one there is no order so you just have to do     array 2  more      2 5   print r  array 2     And sort the keys by whatever you want

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I recently wrote a function to do something similar to what it sounds like you re attempting  it s a similar approach to clasvdb s answer   function magic insert  index  value  input array       if  isset  input array  index           output array   array  index  gt  value       foreach  input array as  k  gt  v          if   k lt  index             output array  k     v          else           if  isset  output array  k                  output array  k 1     v            else              output array  k     v                                else        output array    input array       output array  index     value        ksort  output array     return  output array      Basically it inserts at a specific point  but avoids overwriting by shifting all items down

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Using array splice instead of array slice gives one less function call    toto    array     zero     gt   0      one      gt   1      two      gt   2      three    gt   3      ret   array splice  toto  3     toto    toto    array  my key    gt   my value      ret  print r  toto

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try this one      key pos 0   a1 array  quot a quot   gt  quot red quot    quot b quot   gt  quot green quot    quot c quot   gt  quot blue quot    quot d quot   gt  quot yellow quot     arrkey array keys  a1   array walk  arrkey function  val  key  use  amp  key pos      if  val   b                  key pos  key               a2 array  quot e quot   gt  quot purple quot     newArray   array slice  a1  0   key pos  true     a2           array slice  a1   key pos  NULL  true   print r  newArray    Output Array          a    gt  red        e    gt  purple        b    gt  green        c    gt  blue        d    gt  yellow

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code   function insertValueAtPosition  arr   insertedArray   position         i   0       new array         foreach   arr as  key   gt   value            if   i     position                foreach   insertedArray as  ikey   gt   ivalue                     new array  ikey     ivalue                                   new array  key     value           i              return  new array      example    array            A  8   K   gt 3    insert array     D   9    insertValueAtPosition  array   insert array   position 2      result      gt    A   gt 8    D   gt 9    K   gt 3     May not really look perfect  but it works

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In case you are just looking to insert an item into an array at a certain position  based on  clausvdb answer    function array insert  arr   insert   position         i   0       ret   array        foreach   arr as  key   gt   value                if   i     position                     ret      insert                             ret      value               i              return  ret

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This is an old question  but I posted a comment in 2014 and frequently come back to this  I thought I would leave a full answer  This isn t the shortest solution but it is quite easy to understand   Insert a new value into an associative array  at a numbered position  preserving keys  and preserving order    columns   array       id    gt   ID        name    gt   Name        email    gt   Email        count    gt   Number of posts       columns   array merge      array slice   columns  0  3  true           The first 3 items from the old array     array   subscribed    gt   Subscribed          New value to add after the 3rd item     array slice   columns  3  null  true        Other items after the 3rd     print r   columns        Array         id    gt  ID       name    gt  Name       email    gt  Email       subscribed    gt  Subscribed       count    gt  Number of posts

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Here is my version              Insert an element after an index in an array     param array  array       param string int  key      param mixed  value     param string int  offset     return mixed     function array splice associative  array   key   value   offset        if   is array  array             return  array            if  array key exists  key   array             unset  array  key               return   array         inserted   false      foreach   array as  k   gt   v             return  k     v          if   k     offset  amp  amp    inserted                 return  key     value               inserted   true                      if    inserted             return  key     value              return  return

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I do that as        slightly damaged   array merge          array slice  slightly damaged  0  4  true      4    gt   0 0             array slice  slightly damaged  4  count  slightly damaged  - 4  true

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list   array   Tunisia    gt   Tunis    Germany    gt   Berlin    Italy    gt   Rom    Egypt    gt   Cairo      afterIndex   2   newVal  array  Palestine    gt   Jerusalem      newList   array merge array slice  list 0  afterIndex 1    newVal array slice  list  afterIndex 1

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I just created an ArrayHelper class that would make this very easy for numeric indexes    class ArrayHelper                  Inserts a value at the given position or throws an exception if         the position is out of range          This function will push the current values up in index  ex  if          you insert at index 1 then the previous value at index 1 will          be pushed to index 2 and so on           pos  The position where the inserted value should be placed           Starts at 0             public static function insertValueAtPos array  amp  array   pos   value             maxIndex   count  array -1           if   pos     0                array unshift  array   value             elseif    pos  gt  0   amp  amp    pos  lt    maxIndex                  firstHalf   array slice  array  0   pos                secondHalf   array slice  array   pos                array   array merge  firstHalf  array  value    secondHalf             else               throw new IndexOutOfBoundsException                         Example    array   array  a    b    c    d    e     insertValue    insert    ArrayHelper  insertValueAtPos  array  3   insertValue     Beginning  array   Array         0    gt  a       1    gt  b       2    gt  c       3    gt  d       4    gt  e      Result   Array         0    gt  a       1    gt  b       2    gt  c       3    gt  insert       4    gt  d       5    gt  e

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You can insert elements during a foreach loop  since this loop works on a copy of the original array  but you have to keep track of the number of inserted lines  I call this  bloat  in this code     bloat 0  foreach   Lines as  n  gt  Line            if  MustInsertLineHere  Line                     array splice  Lines  n  bloat 0  string to insert               bloat                    Obviously  you can generalize this  bloat  idea to handle arbitrary insertions and deletions during the foreach loop

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Not as concrete as the answer of Artefacto  but based in his suggestion of using array slice    I wrote the next function   function arrayInsert  target   byKey   byOffset   valuesToInsert   afterKey        if  isset  byKey             if  is numeric  byKey    byKey    int floor  byKey            offset   0           foreach   target as  key   gt   value                if   key      byKey  break               offset                       if   afterKey   offset          else            offset    byOffset              targetLength   count  target        targetA   array slice  target  0   offset  true        targetB   array slice  target   offset   targetLength  true       return array merge  targetA   valuesToInsert   targetB       Features    Inserting one or m  ltiple values Inserting key value pair s  Inserting before after the key  or by offset   Usage examples    target          banana    gt  12       potatoe    gt  6       watermelon    gt  8       apple    gt  7      2   gt  21       pear    gt  6        Values must be nested in an array  insertValues          orange    gt  0       lemon    gt  3      3        By key    Third parameter is not applicable        Insert after 2  before  pear   var dump arrayInsert  target  2  null   valuesToInsert  true           Insert before  watermelon  var dump arrayInsert  target   watermelon   null   valuesToInsert  false         By offset    Second and last parameter are not applicable        Insert in position 2  zero based i e  before  watermelon   var dump arrayInsert  target  null  2   valuesToInsert  null

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Here s a simple function that you could use  Just plug n play     This is Insert By Index  Not By Value    you can choose to pass the array  or use one that you already have declared    EDIT  Shorter Version       function insert  array   index   val               size   count  array     because I am going to use this more than one time        if   is int  index      index  lt  0     index  gt   size                      return -1                  else                      temp     array slice  array  0   index               temp      val             return array merge  temp  array slice  array   index   size                        function insert  array   index   val      function decleration      temp   array       this temp array will hold the value       size   count  array     because I am going to use this more than one time        Validation -- validate if index value is proper  you can omit this part                 if   is int  index      index  lt  0     index  gt   size                echo  Error  Wrong index at Insert  Index       index     Current Size       size              echo   lt br  gt                return false                      here is the actual insertion code       slice part of the array from 0 to insertion index      temp   array slice  array  0   index    e g index 5  then slice will result elements  0-4        add the value at the end of the temp array   at the insertion index e g 5     array push  temp   val         reconnect the remaining part of the array to the current temp      temp   array merge  temp  array slice  array   index   size          array    temp   swap   no need for this if you pass the array cuz you can simply return  temp  but  if u r using a class array for example  this is useful         return  array     you can return  temp instead if you don t use class array     Now you can test the code using     1  result   insert array 1 2 3 4 5  0  0   echo   lt pre gt    echo   lt br  gt    print r  result   echo   lt  pre gt      2  result   insert array 1 2 3 4 5  2   a    echo   lt pre gt    print r  result   echo   lt  pre gt      3  result   insert array 1 2 3 4 5   4   b    echo   lt pre gt    print r  result   echo   lt  pre gt      4  result   insert array 1 2 3 4 5  5  6   echo   lt pre gt    echo   lt br  gt    print r  result   echo   lt  pre gt      And the result is      1 Array        0    gt  0      1    gt  1      2    gt  2      3    gt  3      4    gt  4      5    gt  5     2 Array        0    gt  1      1    gt  2      2    gt  a      3    gt  3      4    gt  4      5    gt  5     3 Array        0    gt  1      1    gt  2      2    gt  3      3    gt  4      4    gt  b      5    gt  5      4 Array        0    gt  1      1    gt  2      2    gt  3      3    gt  4      4    gt  5      5    gt  6

User · Answer

Cleaner approach  based on fluidity of use and less code           Insert data at position given the target key         param array  array     param mixed  target key     param mixed  insert key     param mixed  insert val     param bool  insert after     param bool  append on fail     param array  out     return array     function array insert      array  array        target key        insert key        insert val   null       insert after   true       append on fail   false       out             foreach   array as  key   gt   value            if   insert after   out  key     value          if   key     target key   out  insert key     insert val          if    insert after   out  key     value             if   isset  array  target key    amp  amp   append on fail             out  insert key     insert val             return  out      Usage    colors          blue    gt   Blue        green    gt   Green        orange    gt   Orange        colors   array insert  colors   blue    pink    Pink     die var dump  colors

User · Answer

Very simple 2 string answer to your question    array 1   array     0    gt   zero      1    gt   one      2    gt   two      3    gt   three        At first you insert anything to your third element with array splice and then assign a value to this element   array splice  array 1  3  0   true    array 1 3    array  sample key    gt   sample value

User · Answer

Simplest solution  if you want to insert  an element or array  after a certain key   function array splice after key  array   key   array to insert         key pos   array search  key  array keys  array        if  key pos     false            key pos             second array   array splice  array   key pos            array   array merge  array   array to insert   second array             return  array      So  if you have    array          one    gt  1       three    gt  3     array to insert     two    gt  2     And execute    result array   array splice after key  array   one    array to insert     You ll have   Array          one     gt  1        two     gt  2        three     gt  3

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I needed something that could do an insert before  replace  after the key  and add at the start or end of the array if target key is not found  Default is to insert after the key   New Function         Insert element into an array at a specific key         param array  input array      The original array      param array  insert      The element that is getting inserted  array key   gt  value       param string  target key      The key name      param int  location      1 is after  0 is replace  -1 is before         return array      The new array with the element merged in      function insert into array at key array  input array  array  insert   target key   location   1       output   array       new value   reset  insert      new key   key  insert     foreach   input array as  key   gt   value        if   key      target key             Insert before        if   location    -1             output  new key     new value           output  key     value                   Replace        if   location    0             output  new key     new value                   After        if   location    1             output  key     value           output  new key     new value                    else            Pick next key if there is an number collision        if  is numeric  key             while  isset  output  key                 key                             output  key     value                 Add to array if not found    if   isset  output  new key             Before everything      if   location    -1           output    insert    output               After everything      if   location    1           output  new key     new value               return  output      Input code   array 1   array     0    gt   zero      1    gt   one      2    gt   two      3    gt   three       array 2   array     zero     gt   0      one      gt   1      two      gt   2      three    gt   3        array 1   insert into array at key  array 1  array  sample key    gt   sample value    2  1   print r  array 1    array 2   insert into array at key  array 2  array  sample key    gt   sample value     two   1   print r  array 2     Output  Array        0    gt  zero      1    gt  one      2    gt  two      sample key    gt  sample value      3    gt  three   Array        zero    gt  0      one    gt  1      two    gt  2      sample key    gt  sample value      three    gt  3

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This is another solution in PHP 7 1                   param array  input    Input array to add items to         param array  items    Items to insert  as an array          param int    position Position to inject items from  starts from 0                 return array             function arrayInject  array  input  array  items  int  position    array                if  0  gt    position                return array merge  items   input                     if   position  gt   count  input                 return array merge  input   items                      return array merge              array slice  input  0   position  true                items              array slice  input   position  null  true

User · Answer

If you don t know that you want to insert it at position  3  but you know the key that you want to insert it after  I cooked up this little function after seeing this question              Inserts any number of scalars or arrays at the point        in the haystack immediately after the search key   needle  was found         or at the end if the needle is not found or not supplied         Modifies  haystack in place          param array  amp  haystack the associative array to search  This will be modified by the function         param string  needle the key to search for         param mixed  stuff one or more arrays or scalars to be inserted into  haystack         return int the index at which  needle was found                                      function array insert after  amp  haystack   needle        stuff           if    is array  haystack    return  haystack            new array   array            for   i   2   i  lt  func num args       i                arg   func get arg  i               if  is array  arg    new array   array merge  new array   arg               else  new array      arg                      i   0          foreach  haystack as  key   gt   value                  i              if   key     needle  break                      haystack   array merge array slice  haystack  0   i  true    new array  array slice  haystack   i  null  true             return  i          Here s a codepad fiddle to see it in action  http   codepad org 5WlKFKfz  Note  array splice   would have been a lot more efficient than array merge array slice    but then the keys of your inserted arrays would have been lost  Sigh

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This function supports     both numeric and assoc keys insert before or after the founded key append to the end of array if key isn t founded     function insert into array   array   search key   insert key   insert value   insert after founded key   true   append if not found   false               new array   array             foreach   array as  key   gt   value                    INSERT BEFORE THE CURRENT KEY                  ONLY IF CURRENT KEY IS THE KEY WE ARE SEARCHING FOR  AND WE WANT TO INSERT BEFORE THAT FOUNDED KEY             if   key      search key  amp  amp     insert after founded key                    new array   insert key      insert value                  COPY THE CURRENT KEY VALUE FROM OLD ARRAY TO A NEW ARRAY              new array   key      value                  INSERT AFTER THE CURRENT KEY                  ONLY IF CURRENT KEY IS THE KEY WE ARE SEARCHING FOR  AND WE WANT TO INSERT AFTER THAT FOUNDED KEY             if   key      search key  amp  amp   insert after founded key                    new array   insert key      insert value                         APPEND IF KEY ISNT FOUNDED         if   append if not found  amp  amp  count   array      count   new array                  new array   insert key      insert value           return  new array           USAGE        array1   array          0   gt   zero           1   gt   one           2   gt   two           3   gt   three           4   gt   four               array2   array           zero     gt     0            one      gt     1            two      gt     2            three    gt     3            four     gt     4               array3   array          0   gt   zero           1   gt   one          64   gt   64           3   gt   three           4   gt   four                  INSERT AFTER WITH NUMERIC KEYS     print r  insert into array   array1  3   three     three  value              INSERT AFTER WITH ASSOC KEYS     print r  insert into array   array2   three    three     three  value              INSERT BEFORE     print r  insert into array   array3  64   before-64    before-64 value   false             APPEND IF SEARCH KEY ISNT FOUNDED     print r  insert into array   array3   undefined assoc key    new key    new value   true  true       RESULTS   Array        0    gt  zero      1    gt  one      2    gt  two      3    gt  three      three     gt  three  value      4    gt  four   Array        zero    gt    0      one    gt    1      two    gt    2      three    gt    3      three     gt  three  value      four    gt    4   Array        0    gt  zero      1    gt  one      before-64    gt  before-64 value      64    gt  64      3    gt  three      4    gt  four   Array        0    gt  zero      1    gt  one      64    gt  64      3    gt  three      4    gt  four      new key    gt  new value

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array slice   can be used to extract parts of the array  and the union array operator     can recombine the parts    res   array slice  array  0  3  true        array  my key    gt   my value         array slice  array  3  count  array -3  true     This example    array   array     zero     gt   0      one      gt   1      two      gt   2      three    gt   3       res   array slice  array  0  3  true        array  my key    gt   my value         array slice  array  3  count  array  - 1  true    print r  res     gives    Array        zero     0      one     1      two     2      my key     my value      three     3

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This is better method how insert item to array on some position   function arrayInsert  array   item   position         begin   array slice  array  0   position       array push  begin   item        end   array slice  array   position        resultArray   array merge  begin   end       return  resultArray

User · Answer

easy way   using array splice     array 1   array     0    gt   zero      1    gt   one      2    gt   two      3    gt   three        addArray   array  sample key    gt   sample value     array splice  rs  3  0   addArray     Result    Array        0    gt  zero      1    gt  one      2    gt  two      3    gt  sample value      4    gt  three

[php] How to insert element into arrays at specific position?

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