Question

I have two arrays. Now i want to compare some elements in from both arrays based on that i need to populate one array element to the new array.

 Array1: $days this is an array of elements between two dates.

$days = Array
       (
         [0] => 2012-06-23
         [1] => 2012-06-24
         [2] => 2012-06-25
         [3] => 2012-06-26
         [4] => 2012-06-27
         [5] => 2012-06-28
         [6] => 2012-06-29
         [7] => 2012-06-30
         [8] => 2012-07-01
         [9] => 2012-07-02
         [10] => 2012-07-03
         [11] => 2012-07-04
         [12] => 2012-07-05
         [13] => 2012-07-06
         [14] => 2012-07-07
         [15] => 2012-07-08
         [16] => 2012-07-09
         [17] => 2012-07-10
         [18] => 2012-07-11
         [19] => 2012-07-12
         [20] => 2012-07-13
         [21] => 2012-07-14
         [22] => 2012-07-15
         [23] => 2012-07-16
        )

 Array2: $summary is the array which i am getting from the database..

 $summary = Array
 (
    [0] => Array
    (
        [date] => 2012-06-23 
        [no_of_posts] => 1
    )

    [1] => Array
    (
        [date] => 2012-06-24 
        [no_of_posts] => 2
    )

    [2] => Array
    (
        [date] => 2012-06-25 
        [no_of_posts] => 1
    )

    [3] => Array
    (
        [date] => 2012-06-26 
        [no_of_posts] => 1
    )

    [4] => Array
    (
        [date] => 2012-06-27
        [no_of_posts] => 1
    )

Now from these both arrays i need an array which tells me on this date this many times posts are there if there no posts against one date then it should be zero for that. I tried like this…..

    $result = array();
   foreach($summary as $key=>$s) {
       foreach($days as $d) {
          if($s['date'] == $d) {
               $result[$d] = $s['no_of_posts'];
          } else {
               $result[$d] = 0;
          }
      }
   }

I know there is mistake i can’t able to find………..any ideas.

Output array need to look like below…..

    $result = Array
            Array
       (
         [2012-06-23] = 1
         [2012-06-24] = 2
         [2012-06-25] = 1
         [2012-06-26] = 1
         [2012-06-27] = 1
         [2012-06-28] = 0
         [2012-06-29] = 0
         [2012-06-30] = 0
         [2012-07-01] = 0
         [2012-07-02] = 0
         [2012-07-03] = 0
         [2012-07-04] = 0
         [2012-07-05] = 0
         [2012-07-06] = 0
         [2012-07-07] = 0
         [2012-07-08] = 0
         [2012-07-09] = 0
         [2012-07-10] = 0
         [2012-07-11] = 0
         [2012-07-12] = 0 
         [2012-07-13] = 0
         [2012-07-14] = 0
         [2012-07-15] = 0
         [2012-07-16] = 0
        )

Answer 1

The quickest way is to loop through your database results and create a values array indexed by date:

$summaryTotals = array();
foreach($summary as $dbSummary) {
    $summaryTotals[$dbSummary['date']] = $dbSummary['no_of_posts'];
}

Then iterate through your dates array inputting the values where a match occurs in the summary array, like so:

$dayValues = array();
foreach($days as $day) {
    if(isset($summaryTotals[$day])) {
        $dayValues[$day] = $summaryTotals[$day];
    } else {
        $dayValues[$day] = 0;
    }
}

The dayValues array should now be what you’re after. I believe.