Creating 2-D matrix in php
That would be
$this->map[10010012][10010015]= MAX_DISTANCE;
On the other hand, why do you want to set all empty/non-existing cell to MAX_DISTANCE? You can leave the map incomplete and whenever a cell does not exist you assume MAX_DISTANCE as its value.
edit: simple example
define('MAX_DISTANCE', PHP_INT_MAX);
$map = array(
10010012 => array ( 10010013 => 2, 10010016 => 8),
10010016 => array ( 10010015 => 5 ),
10010013 => array ( 10010014 => 7, 10010016 => 3),
10010014 => array ( 10010015 => 2 )
);
function getValue(&$map, $x, $y) {
return isset($map[$x][$y]) ? $map[$x][$y] : MAX_DISTANCE;
}
function setValue(&$map, $x, $y, $value) {
if ( !isset($map[$x]) ) {
$map[$x] = array($y => $value);
}
else {
$map[$x][$y] = $value;
}
}
// get an "existing" value from $map
echo getValue($map, 10010012, 10010016), "\n";
// get a "non-existing" value from $map
echo getValue($map, 10010014, 10010016), "\n";
// set a "new" value
setValue($map, 10010014, 10010016, 5);
// $map has been altered
var_dump($map[10010014]);
prints
8
2147483647
array(2) {
[10010015]=>
int(2)
[10010016]=>
int(5)
}
5lackp1x3l0x17
Updated on October 02, 2022Comments
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5lackp1x3l0x17 over 1 year
The thing is I have to create a 2D matrix in php where each row and column must have a key. I tried to do this but what happens is that a 2-D array is created which does not resemble a matrix. I used the following code:
$x=$row['start_id'];
$y=$row['dest_id'];
$d=$row['distance'];
$this->map[$x][$y]=$d;Here map is the intended matrix. The intention of this code is to create an adjacency matrix and then fill the unset cells with maximum distance. $x, $y and $d in above code are derived from result of a mysql query.
Sample Output:
Array ( [10010012] => Array ( [10010013] => 2 [10010016] => 8 ) [10010016] => Array ( [10010015] => 5 ) [10010013] => Array ( [10010014] => 7 [10010016] => 3 ) [10010014] => Array ( [10010015] => 2 ) )
Now the problem is that I am not able to fill the empty cells
e.g. row key =>[10010012] and column key=>[10010015] (Not able to set value)Any help is appreciated. If possible also mention how to traverse through such matrices.
I am a relative beginner and have tried my best to explain my problem. However if you find any shortcomings please point them out.
Edit: The matrix is not a square one.
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Franz over 14 years"Not able"? What exactly is the error message or what doesn't work?
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5lackp1x3l0x17 over 14 yearsIts not an error message. I am creating a matrix using an associative array in the wrong manner. There seems to be some problem in the logic.
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5lackp1x3l0x17 over 14 yearsI cant possibly manually add max_distance to every cell. It is supposed to be automatic using a foreach loop which will set max_distance whenever it finds an unset cell.
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VolkerK over 14 yearsBut why set MAX_DISTANCE anyway? Why not consider "not set at all equals MAX_DISTANCE" as shown in the example? The second getValue(), i.e.
getValue($map, 10010014, 10010016)
returns MAX_DISTANCE because there is no $map[10010014][10010016] (yet). Please elaborate why this isn't sufficient. -
5lackp1x3l0x17 over 14 yearsDidnt see your edit. Now I understand what you mean to say. I will try to implement your solution and get back to you.
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5lackp1x3l0x17 over 14 yearsThanks a lot for your quick answer.