Create new array based on element position

Question

I have an array like so

$dataArray = array(
    array( 20800, 21679, 0 ),
    array( 15254, 0, 3726 ),
    array( 17426, 2973, 0 ),
    array( 4391, 37, 0 ),
    array( 39194, 435, 0 )
);

I am creating a sub array from this. Any value greater than 2000 becomes a 1, otherwise it becomes a 0.

foreach ($dataArray as $row => $data) {
    foreach ($data as $key => $value) {
        if($value > 1999) {
            $dataArray[$row][$key] = 1;
        } else {
            $dataArray[$row][$key] = 0;
        }
    }
}

This produces the following

$dataArray = array(
    array( 1, 1, 0 ),
    array( 1, 0, 1 ),
    array( 1, 1, 0 ),
    array( 1, 0, 0 ),
    array( 1, 0, 0 )
);

Now what I am trying to do is produce another array that shows the positions of the 1's within the above array. Each row should be represented by a new array. The output I am looking for is this

$dataArray = array(
    array( 1, 2 ),
    array( 1, 3 ),
    array( 1, 2 ),
    array( 1 ),
    array( 1 )
);

So I can see that row 1 has a 1 in position 1 and 2, row 2 has a 1 in positions 1 and 3 etc.

I wanted to make use of my current loop, so I am trying something like this

$position = array();

foreach ($dataArray as $row => $data) {
    foreach ($data as $key => $value) {
        if($value > 1999) {
            $position[$row] = $key + 1;
            $dataArray[$row][$key] = 1;
        } else {
            $dataArray[$row][$key] = 0;
        }
    }
}

But this seems way off according to my output. How can I achieve what I am after?

Thanks

$position[$row][]

Patrick Q
– Patrick Q

2018-10-11 19:22:12 +00:00
Commented Oct 11, 2018 at 19:22 — Patrick Q
– Patrick Q, Commented Oct 11, 2018 at 19:22

sietse85 · Accepted Answer · 2018-10-11 19:42:41Z

2

<?php
$dataArray = array(
    array( 20800, 21679, 0 ),
    array( 15254, 0, 3726 ),
    array( 17426, 2973, 0 ),
    array( 4391, 37, 0 ),
    array( 39194, 435, 0 )
);
$endResult = [];

foreach ($dataArray as $key => $value) {
   foreach ($value as $subkey => $subvalue) {
    if ($subvalue >= 2000) {
       $endResult[$key][] = $subkey +1;
    }
   }
}

print_r($endResult);

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

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

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

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

[4] => Array
    (
        [0] => 1
    )
)

edited Oct 11, 2018 at 19:42

answered Oct 11, 2018 at 19:23

sietse85

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3 Comments

katie hudson Over a year ago

I like this solution the most as it skips creating the initial array with 1s and 0s, thanks

sietse85 Over a year ago

don't forget to use short array syntax as of PHP5.6 ;) [ ]

Nigel Ren Over a year ago

You could use $key instead of $i

Jeto · Accepted Answer · 2018-10-11 19:21:31Z

2

You could use array_map along with array_keys:

$dataArray = [
  [1, 1, 0],
  [1, 0, 1],
  [1, 1, 0],
  [1, 0, 0],
  [1, 0, 0]
];

$onePositions = array_map(function($row) {
  return array_map(function($position) { return $position + 1; }, array_keys($row, 1));
}, $dataArray);

echo '<pre>'; var_dump($onePositions); echo '</pre>';

Demo here

answered Oct 11, 2018 at 19:21

Jeto

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Comments

mtr.web · Accepted Answer · 2018-10-11 19:24:45Z

1

You can make use of the second parameter in the array_keys() function to get the positions after you populate the ones and zeros:

$position = array();
$binary = array();

foreach ($dataArray as $row => $data) {

    // if you want to have the positions start at 1 instead of 0
    // add a dummy value to the final array
    $binary[$row][] = 0;

    foreach ($data as $key => $value) {
        if($value > 1999) {
            $binary[$row][] = 1;
        } else {
            $binary[$row][] = 0;
        }
    }
    $positions[] = array_keys($binary[$row], 1);
}

Demo Here

answered Oct 11, 2018 at 19:24

mtr.web

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