CODEWITHSUNDEEP
phparraysforeachechodelay
Francesco
Francesco

Reputation: 95

How to echo the latest time a value appear into a set of arrays

I have 10 sets of numbers into array, representing different days.

<?php 
$day1 = ['23', '11', '52', '33', '1', '4']; 
$day2 = ['66', '70', '55', '8', '22', '1'];
$day3 = ['38', '21', '52', '51', '53', '9'];
$day4 = ['14', '31', '54', '5', '73', '39'];
$day5 = ['10', '3', '22', '59', '73', '39'];
$day6 = ['22', '13', '4', '5', '73', '39'];
$day7 = ['40', '3', '22', '5', '13', '30'];
$day8 = ['88', '53', '4', '25', '71', '19'];
$day9 = ['10', '30', '49', '25', '73', '46'];
$day10 = ['10', '3', '4', '5', '73', '11'];

I need to echo the latest time a number has been seen into the sets, considering that $day1 is the older moment, while $day10 is the most recent.

Example : number 73 appears in day 4, 5, 6, 9 and 10, but I'm interested only in the most recent one so I should print

73 last seen on day 10

I would like to be able also to print aggregate values, like this :

last seen since day 10 : '10', '3', '4', '5', '73', '11'
last seen since day 9 : '30', '49', '25', '46'
last seen since day 8 : '88', '53', '71', '19'
last seen since day 7 : '40', '22'. '13'

I'm really new to php, so i was trying by exploding the values, then introducing a foreach cycle

enter $myArray1 = explode(" " $day1);
$myArray2 = explode(" " $day2);
$myArray3 = explode(" " $day3);
$myArray4 = explode(" " $day4);
$myArray5 = explode(" " $day5);
$myArray6 = explode(" " $day6);
$myArray7 = explode(" " $day7);
$myArray8 = explode(" " $day8);
$myArray9 = explode(" " $day9);
$myArray10 = explode(" " $day10);
print_r ($myArray1);
foreach ($myArray1 as $value);
{   
echo "$value <br>";
$array[] = $value;
}

But I'm definetely clueless. Can anyone help me ? thanks

Upvotes: 0

Views: 65

Answers (2)

AbraCadaver
AbraCadaver

Reputation: 78994

First off, use an array of arrays with the day number as the index:

$days[1] = ['23', '11', '52', '33', '1', '4']; 
$days[2] = ['66', '70', '55', '8', '22', '1'];
$days[3] = ['38', '21', '52', '51', '53', '9'];

Then something like:

$find = '1';
$latest = 'never';

foreach($days as $day => $values) {
    if(in_array($find, $values)) {
        $latest = $day;
    }
}
echo "$find last seen on day $latest";

To get aggregates you might loop and build an array indexed on the value with the latest day as the array value:

$aggregate = [];
foreach($days as $day => $values) {
    $aggregate = array_replace($aggregate, array_fill_keys($values, $day));
}

Will result in something like:

(
    [23] => 1
    [11] => 1
    [52] => 3
    [33] => 1
    [1] => 2
    [4] => 1
    [66] => 2
    [70] => 2
    [55] => 2
    [8] => 2
    [22] => 2
    [38] => 3
    [21] => 3
    [51] => 3
    [53] => 3
    [9] => 3
)

That you can use by getting the indexes for the elements that have day as the value:

echo "last seen day 1" . implode(', ', array_keys($aggregate, '1'));

Then you can use that for the first part as well:

echo "1 last seen on day {$aggregate[1]}";

Upvotes: 1

Top-Master
Top-Master

Reputation: 8751

// First of all, convert days to 2D array.
$dayList = [];
$dayList[] = $day1;
$dayList[] = $day2;
$dayList[] = ...;

// Cache last-seen time for each number.
$lastSeen = [];
foreach ($dayList as $dayId => $day) {
   foreach ($day as $number) {
      $lastSeen[$number] = $dayId;
   }
}

// At last, maybe sort the array, but now we have a list,
// with numbers as key and last-seen day-index as value
// (so, use plus one to get number instead of index).

echo '73 was last seen at day:' . ($lastSeen[73] + 1);

print_r($lastSeen);

Upvotes: 0

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