Map dates array with values array and group by day of the week filling missing dates with 0 values

Question

I have an array of dates and values, for example:

$dates = ['2014-12-01', '2014-12-02', '2014-12-08', '2014-12-09', '2014-12-10', '2014-12-11'];
$values = [5, 3, 7, 8, 9, 2];

You'll note that 12/01 is a Monday, as is 12/08. I'd like to group data from these two arrays by day if the week:

[
    'monday' => [5, 7],
    'tuesday' => [3, 8],
    'wednesday' => [0, 9],
    'thursday' => [0, 2],
]

You'll note that the arrays are formed by grabbing the values associated with the days of the week. However, in the case that a Wednesday date exists, for example, but the prior Tuesday does not, then the array should have a "0". In other words, the 4 arrays should all be the same length.

NOTE: So far, I have only determined how to find the day of the week from a date: date('l', strtotime("2014-12-08")); I really can't figure out the general algorithm to solve this.

Have you made an attempt yet? It would be helpful to see it. — showdev
– showdev, Commented Dec 12, 2014 at 22:18
A general algorithm: Iterate through the date array. For each date's key/value, determine the day of the week. Add the value for the same key from the values array to an array with a key that corresponds to the day of the week. — showdev
– showdev, Commented Dec 12, 2014 at 22:21
@showdev thanks a lot for your idea. I'm a little bit confused, however. Do you think you could write php code to do this? For example, what happens when a "Monday" is encountered and then the next date is also a "Monday". It seems more complicated than what you wrote. — CodeGuy
– CodeGuy, Commented Dec 12, 2014 at 22:23
You can append to the "week" array: $weekdays[$day_of_week][]=$values[$dates_key]; I'm sorry, I don't want to write all the code -- nothing personal. But the SO community will help to troubleshoot your code if you make an attempt and have trouble. — showdev
– showdev, Commented Dec 12, 2014 at 22:25

Cheery · Accepted Answer · 2014-12-12 22:55:21Z

1

$dates  = array( '2014-12-01','2014-12-02','2014-12-08','2014-12-09',
                 '2014-12-10','2014-12-11' );
$values = array( 5, 3, 7, 8, 9, 2 );

$date  = strtotime(min($dates));
$stop  = strtotime(max($dates));
$dates = array_flip($dates);
$out   = array();

while($date <= $stop)
{
   $tmp = date('Y-m-d', $date);
   $out[date('l', $date)][] = isset($dates[$tmp]) && isset($values[$dates[$tmp]]) ?
                              $values[$dates[$tmp]] : 0;  
   $date = strtotime('+1 day', $date);   
}

print_r($out);

Result:

Array
(
    [Monday] => Array
        (
            [0] => 5
            [1] => 7
        )

    [Tuesday] => Array
        (
            [0] => 3
            [1] => 8
        )

    [Wednesday] => Array
        (
            [0] => 0
            [1] => 9
        )

    [Thursday] => Array
        (
            [0] => 0
            [1] => 2
        )

    [Friday] => Array
        (
            [0] => 0
        )

    [Saturday] => Array
        (
            [0] => 0
        )

    [Sunday] => Array
        (
            [0] => 0
        )

)

ps: how can I get the an array of all the dates included in the "dates" array associated with only all the Mondays?

Modify the code as, for example:

   $tmp = date('Y-m-d', $date);
   $exists = isset($dates[$tmp]) && isset($values[$dates[$tmp]]);
   $out[date('l', $date)]['numbers'][] = $exists ? $values[$dates[$tmp]] : 0; 
   if ($exists) $out[date('l', $date)]['dates'][] = $tmp;
   $date = strtotime('+1 day', $date);

You'll get an output as (example for monday)

[Monday] => Array
    (
        [numbers] => Array
            (
                [0] => 5
                [1] => 7
            )

        [dates] => Array
            (
                [0] => 2014-12-01
                [1] => 2014-12-08
            )

    )

edited Dec 12, 2014 at 22:55

answered Dec 12, 2014 at 22:45

Cheery

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6 Comments

Cheery Over a year ago

@CodeGuy not sure what you are talking about. $monday = $out['Monday']; .. and so on?

CodeGuy Over a year ago

thanks so much!! Sorry, I was trying to ask: how can I get the an array of all the dates included in the "dates" array associated with only all the Mondays?

CodeGuy Over a year ago

great, thanks! One last thing: this assumes the dates are in order. What if the dates aren't in order such that the dates and associated indices should be sorted. How could I do that?

Cheery Over a year ago

@CodeGuy My code does not care about order of the dates as long as $values and $dates correspond to each other. But if you really need it - stackoverflow.com/a/9917886/1164491

Cheery Over a year ago

@CodeGuy give me example of data. It should not depend on the order. or are you looking at the values in [dates] => Array? Check the link above.

|

AbraCadaver · Accepted Answer · 2014-12-12 22:36:26Z

0

Might be a better way to get the 0s in there without another loop but I'm headed out:

foreach($dates as $key => $val) {
    $day = date('l', strtotime($val));
    $result[$day][] = $values[$key];
}
foreach($result as &$val) {
    if(count($val) == 1) {
        array_unshift($val, 0);
    }
}
print_r($result);

answered Dec 12, 2014 at 22:36

AbraCadaver

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