how to key map an array in php

Question

I have an array as follows

array(2) { ["name"]=> string(36) "newyork" ["categoryid"]=> string(1) "4" }                                                                                                                                                                                                            
array(2) { ["name"]=> string(24) "michigun" ["categoryid"]=> string(1) "4" } 
array(2) { ["name"]=> string(27) "canada" ["categoryid"]=> string(1) "5" }             
array(2) { ["name"]=> string(35) "manhatten" ["categoryid"]=> string(1) "5"   
}

i want to have a new array where i will have

 {"4" => newyork,michigun}
 {"5" => canada,manhatten}

.. how can it be done? pls help.

i tried foreach($key => $value) but i m not sure about the logic. — Ketki Nimdeo
– Ketki Nimdeo, Commented Jul 29, 2015 at 5:59
you want to add in this array or something else? please paste your desired outcome.Thanks. — Death-is-the-real-truth
– Death-is-the-real-truth, Commented Jul 29, 2015 at 6:00
i want a new array which will print {"4" => newyork,michigun} {"5" => canada,manhatten} — Ketki Nimdeo
– Ketki Nimdeo, Commented Jul 29, 2015 at 6:01

Sougata Bose · Accepted Answer · 2015-07-29 06:01:22Z

4

You can use a loop and build the array -

$new = array();
foreach($your_array as $array) {
   if(array_key_exists($array['categoryid'], $new)) { // if categoryid is already set the concatenate the name
       $new[$array['categoryid']] = $new[$array['categoryid']] . ',' . $array['name'];
   } else { // set the name
       $new[$array['categoryid']] = $array['name'];
   }
}

answered Jul 29, 2015 at 6:01

Sougata Bose

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2 Comments

Ketki Nimdeo Over a year ago

can u explain the $new[$array['categoryid']] = $new[$array['categoryid']] . ',' . $array['name']; statement ?

Sougata Bose Over a year ago

It will concatenate the name with the value which has index of the categoryid.

bbankowski · Accepted Answer · 2015-07-29 13:42:30Z

4

If don't mind using external lib, it is pretty straightforward with ouzo-goodies:

Arrays::groupBy($array, Functions::extractField('categoryid'));

You can go one step further to join names with commas:

$result = Arrays::groupBy($array, Functions::extractField('categoryid'));
Arrays::map($result, function($value) {
    return Joiner::on(',')->mapValues(Functions::extractField('name'))->join($value);
});

answered Jul 29, 2015 at 13:42

bbankowski

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Comments

EasyCo · Accepted Answer · 2015-07-29 06:12:34Z

1

Uses the PHP 5.4 array syntax: [] instead of array()

Data

$arr = [
  [
    "name" => "newyork",
    "categoryid" => "4"
  ],
  [
    "name" => "michigun",
    "categoryid" => "4"
  ],
  [
    "name" => "canada",
    "categoryid" => "5"
  ],
    [
    "name" => "manhatten",
    "categoryid" => "5"
  ],
];

Parse

$result = [];

foreach ($arr as $el) {
  if (array_key_exists($el['categoryid'], $result)) {
    $result[$el['categoryid']] = $result[$el['categoryid']] . ',' . $el['name'];
  } else {
   $result[$el['categoryid']] = $el['name'];
  }
}


print_r($result);

Result

Array ( [4] => newyork,michigun [5] => canada,manhatten )

edited Jul 29, 2015 at 6:12

answered Jul 29, 2015 at 6:10

EasyCo

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3 Comments

Narendrasingh Sisodia Over a year ago

This is simply copy and paste of this answer

EasyCo Over a year ago

Settle down everybody. @b0s3 just beat me to the punch is all.

Narendrasingh Sisodia Over a year ago

@KetkiNimdeo then how does this answer make difference with this

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