Create new array based on element position - php

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

Answer 1

<?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
)
)

Answer 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

Answer 3

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