将数组合并为一个更简单的数组（PHP）[关闭]

Question

I have an array that looks like this. I'm looking at condensing this down into a simpler array (see below) how would I go about this?

array(1552) {
  [0]=>
  array(2) {
    [0]=>
    string(4) "3792"
    [1]=>
    string(2) "99"
  }
  [1]=>
  array(2) {
    [0]=>
    string(4) "3792"
    [1]=>
    string(3) "100"
  }
  [2]=>
  array(2) {
    [0]=>
    string(4) "3792"
    [1]=>
    string(3) "101"
  }
  [3]=>
  array(2) {
    [0]=>
    string(4) "3792"
    [1]=>
    string(3) "102"
  }
  [4]=>
  array(2) {
    [0]=>
    string(4) "3792"
    [1]=>
    string(3) "103"
  }
  [5]=>
  array(2) {
    [0]=>
    string(4) "3792"
    [1]=>
    string(3) "104"
  }
  [6]=>
  array(2) {
    [0]=>
    string(4) "3832"
    [1]=>
    NULL
  }
}

I would like to condense it down

array(1552) {
  [3792]=>
  array(2) {
    [0]=>
    string(4) "99"
    [1]=>
    string(2) "100"
    [2]=>
    string(2) "101"
    [3]=>
    string(2) "102"
    [3]=>
    string(2) "103"
    [3]=>
    string(2) "104"
  }
  [3832]=>
  array(2) {
    [0]=>
    NULL
  }

Answer 1

This is a quick 'n dirty way to do it

<?php
$result = array();

// assuming your data is named $data...
foreach ($data as $pair) {
  if (!array_key_exists($pair[0], $result)) {
    $result[$pair[0]] = array();
  }
  $result[$pair[0]][] = $pair[1];
}

Another way would be to use array_reduce

$data2 = array_reduce($data, function($res, $pair) {
  if (!array_key_exists($pair[0], $res)) {
    $res[$pair[0]] = array();
  }
  $res[$pair[0]][] = $pair[1];
  return $res;
}, array());