在多维数组中组合字符串并保持键- PHP。

I have this array:

我有这个数组:

array(1) {
  ["comments"]=>
  array(244) {
    [113]=>
      array(2) {
      [0]=>
      string(40) "2016-07-15 09:27 | From On Track to Done"
      [1]=>
      string(40) "2016-07-15 09:56 | From Done to On Track"
     }
  }
}
array(1) {
  ["c