How do you reindex an array in PHP but with indexes starting from 1

Question

I have the following array  which I would like to reindex so the keys are reversed  ideally starting at 1    Current array  edit  the array actually looks like this    Array     2    gt  Object                title    gt  Section          linked    gt  1         1    gt  Object                title    gt  Sub-Section          linked    gt  1         0    gt  Object                title    gt  Sub-Sub-Section          linked    gt              How it should be   Array     1    gt  Object                title    gt  Section          linked    gt  1         2    gt  Object                title    gt  Sub-Section          linked    gt  1         3    gt  Object                title    gt  Sub-Sub-Section          linked    gt

User · Answer

If it s OK to make a new array it s this    result   array    foreach    array as  key   gt   val        result   key 1      val    If you need reversal in-place  you need to run backwards so you don t stomp on indexes that you need   for    k   count  array     k--  gt  0          result   k 1      result   k    unset   array 0          remove the  zero  element

User · Answer

You can reindex an array so the new array starts with an index of 1 like this    arr   array     2    gt   red      1    gt   green      0    gt   blue        arr1   array values  arr        Reindex the array starting from 0  array unshift  arr1              Prepend a dummy element to the start of the array  unset  arr1 0                    Kill the dummy element   print r  arr   print r  arr1     The output from the above is   Array        2    gt  red      1    gt  green      0    gt  blue   Array        1    gt  red      2    gt  green      3    gt  blue

User · Answer

Here s my own implementation  Keys in the input array will be renumbered with incrementing keys starting from  start index   function array reindex  array   start index         array   array values  array        zeros array   array fill 0   start index  null       return array slice array merge  zeros array   array    start index  null  true

User · Answer

I just found out you can also do a  array splice  ar  0  0     That does the re-indexing inplace  so you don t end up with a copy of the original array

User · Answer

tmp   array    foreach  array values  array  as  key   gt   value         tmp  key 1     value     array    tmp

User · Answer

If you are not trying to reorder the array you can just do    array   array reverse   array     array   array reverse   array     The array reverse is very fast and it reorders as it reverses   Someone else showed me this a long time ago   So I can t take credit for coming up with it   But it is very simple and fast

User · Answer

You can easily do it after use array values   and array filter   function together to remove empty array elements and reindex from an array in PHP   array filter   function The PHP array filter   function remove empty array elements or values from an array in PHP  This will also remove blank  null  false  0  zero  values   array values   function The PHP array values   function returns an array containing all the values of an array  The returned array will have numeric keys  starting at 0 and increase by 1   Remove Empty Array Elements and Reindex  First let   s see the  stack array output     lt  php    stack   array  PHP    HTML    CSS        JavaScript   null  0     print r  stack     gt    Output   Array        0    gt  PHP      1    gt  HTML      2    gt  CSS      3    gt        4    gt  JavaScript      5    gt        6    gt  0     In above output we want to remove blank  null  0  zero  values and then reindex array elements  Now we will use array values   and array filter   function together like in below example    lt  php    stack   array  PHP    HTML    CSS        JavaScript   null  0     print r array values array filter  stack       gt    Output   Array        0    gt  PHP      1    gt  HTML      2    gt  CSS      3    gt  JavaScript

User · Answer

A more elegant solution    list   array combine range 1  count  list    array values  list

User · Answer

Here is the best way     Array  array   array  tomato        apple    melon    cherry            banana      that returns  Array        0    gt  tomato      1    gt        2    gt  apple      3    gt  melon      4    gt  cherry      5    gt        6    gt        7    gt  banana     by doing this   array   array values array filter  array      you get this  Array        0    gt  tomato      1    gt  apple      2    gt  melon      3    gt  cherry      4    gt  banana     Explanation  array values     Returns the values of the input array and indexes numerically   array filter     Filters the elements of an array with a user-defined function  UDF If none is provided  all entries in the input table valued FALSE will be deleted

User · Answer

It feels like all of the array combine   answers are all copying the same  mistake   the unnecessary call of array values      array combine   ignores the keys of both parameters that it receives   Code   Demo    array         2   gt   object   title    gt   Section    linked    gt  1       1   gt   object   title    gt   Sub-Section    linked    gt  1       0   gt   object   title    gt   Sub-Sub-Section    linked    gt  null      var export array combine range 1  count  array     array      Output   array     1   gt      object  array        title    gt   Section         linked    gt  1         2   gt      object  array        title    gt   Sub-Section         linked    gt  1         3   gt      object  array        title    gt   Sub-Sub-Section         linked    gt  NULL

User · Answer

You may want to consider why you want to use a 1-based array at all   Zero-based arrays  when using non-associative arrays  are pretty standard  and if you re wanting to output to a UI  most would handle the solution by just increasing the integer upon output to the UI   Think about consistency   both in your application and in the code you work with   when thinking about 1-based indexers for arrays

User · Answer

Duplicate removal and reindex an array    lt  php       oldArray   array  0   gt  php   1   gt  java   2   gt     3   gt  asp   4   gt     5   gt  mysql         duplicate removal     fillteredArray   array filter  oldArray        reindexing actually happens  here     newArray   array merge  filteredArray      print r  newArray     gt

User · Answer

Well  I would like to think that for whatever your end goal is  you wouldn t actually need to modify the array to be 1-based as opposed to 0-based  but could instead handle it at iteration time like Gumbo posted   However  to answer your question  this function should convert any array into a 1-based version  function convertToOneBased   arr         return array combine  range  1  count   arr      array values   arr          EDIT  Here s a more reusable flexible function  should you desire it   arr   array   a    b    c      echo   lt pre gt    print r  reIndexArray   arr      print r  reIndexArray   arr  1      print r  reIndexArray   arr  2      print r  reIndexArray   arr  10      print r  reIndexArray   arr  -10      echo   lt  pre gt     function reIndexArray   arr   startAt 0         return   0     startAt             array values   arr             array combine  range   startAt  count   arr        startAt - 1      array values   arr

User · Answer

If you want to re-index starting to zero  simply do the following    iZero   array values  arr     If you need it to start at one  then use the following    iOne   array combine range 1  count  arr    array values  arr      Here are the manual pages for the functions used    array values   array combine   range

User · Answer

Why reindexing  Just add 1 to the index   foreach   array as  key   gt   val        echo  key   1    lt br gt          Edit      After the question has been clarified  You could use the array values to reset the index starting at 0  Then you could use the algorithm above if you just want printed elements to start at 1

User · Answer

Similar to Nick s contribution  I came to the same solution for reindexing an array  but enhanced the function a little since from PHP version 5 4  it doesn t work because of passing variables by reference  Example reindexing function is then like this using use keyword closure   function indexArrayByElement  array   element         arrayReindexed           array walk           array          function   item   key  use   amp  arrayReindexed   element                 arrayReindexed  item  element      item                       return  arrayReindexed

User · Answer

Sorting is just a sort    reindexing seems a bit silly but if it is needed this will do it  Though not in-place  Use array walk   if you will do this in a bunch of places  just use a for-key-value loop if this is a one-time operation    lt  php  function reindex  amp  item   key   amp  reindexedarr         reindexedarr  key 1     item      arr   Array  2   gt   c   1   gt   b   0   gt   a     sort  arr    newarr   Array    array walk  arr  reindex   amp  newarr    arr    newarr  print r  arr      Array    1    gt  a  2    gt  b  3    gt  c      gt

User · Answer

The fastest way I can think of  array unshift  arr  null   unset  arr 0    print r  arr     And if you just want to reindex the array start at zero  and you have PHP  7 3 you can do it this way  array unshift  arr     I believe array unshift is better than array values as the former does not create a copy of the array

User · Answer

Simply do this    lt  php  array push  array        array   array reverse  array   array shift  array

User · Answer

Similar to  monowerker  I needed to reindex an array using an object s key      new   array     old   array     object array  id    gt  123      object array  id    gt  456      object array  id    gt  789      print r  old    array walk  old  function  item   key   amp  reindexed array       reindexed array  item- gt id     item      amp  new    print r  new     This resulted in   Array        0    gt  stdClass Object                        id    gt  123                1    gt  stdClass Object                        id    gt  456                2    gt  stdClass Object                        id    gt  789             Array        123    gt  stdClass Object                        id    gt  123                456    gt  stdClass Object                        id    gt  456                789    gt  stdClass Object                        id    gt  789

User · Answer

This will do what you want    lt  php   array   array 2   gt   a   1   gt   b   0   gt   c     array unshift  array  false      Add to the start of the array  array   array values  array      Re-number     Remove the first index so we start at 1  array   array slice  array  1  count  array   true    print r  array      Array    1    gt  a  2    gt  b  3    gt  c       gt

[php] How do you reindex an array in PHP but with indexes starting from 1?

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