Converting 1D array to 2D array PHP

Question

I currently have a text file that looks like this:

0000001
0000002
0000003
0000004
0000005
0000006....

I am using the code below to convert 1d array to 2d..

$filename  = "surface.txt";
$fp = fopen($filename, "r");
while(!feof($fp)) {  
     $content = fread($fp, filesize($filename));
     $lines = explode("\n", $content);
   for ($i=0; $i<=$row; $i++){
   for ($j =0; $j<=$col; $j++){
      //echo $lines[$i*$col + $j]; 
      $matrix[$i][$j] = $lines[$i*$col + $j];
      //var_dump($matrix[i][j]); 
     }
    }
   }
 fclose($fp);

My output array $matrix prints all NULL values.I have put var_dump() inside the loop to see what it displays.. Interestingly, It is reading all the values,but, after the last value, it kept on reading empty values too, which inturn made the $matrix empty(NULL) at last. I don't know how to fix this problem. If I am not clear in explaining how the output appears, please look at it below..

Array ( [0] => Array ( [0] => 0000001 ) )
Array ( [0] => Array ( [0] => 0000002 [1] => 0000002 ) )
Array ( [0] => Array ( [0] => 0000001 [1] => 0000002 [2] => 0000003 ) )

In the last lines, I see that the output is like below

  Array ( [0] => Array ( [0] => [1] => [2] => [3] => ) [1] => Array ( [0] => [1] => [2] =>   [3] => ) [2] => Array ( [0] => [1] => [2] => [3] => ) [3] => Array ( [0] => [1] => [2] => [3] => ) [4] => Array ( [0] => [1] => [2] => [3] => ) [5] => Array ( [0] => [1] => [2] => [3] => ) [6] => Array ( [0] => [1] => [2] => [3] => ) )

Any help is highly appreciated..

Where is $col defined? With the indexes for the for loops, you normally start on $i = 0 and the comparison is $i < $col, then you'll compare as many members as numbers in $col (you start by 0). — Francisco Presencia
– Francisco Presencia, Commented Feb 6, 2014 at 13:52
$row and $col are defined in the original file,, I forgot to paste it..Sorry..$row=6; $col=3; Thanks for looking into it — user2791530
– user2791530, Commented Feb 6, 2014 at 13:54
Then check out my suggestion. If there are 6 rows, you want for ($i = 0; $i < $row; $i++). If you use the <= you'd have 7 rows, being the last one undetermined. Same with $col. — Francisco Presencia
– Francisco Presencia, Commented Feb 6, 2014 at 13:56
I did the correction and ran the code..it corrected the rows issue but, It is still dumping Null values. — user2791530
– user2791530, Commented Feb 6, 2014 at 13:59

user2791530 · Accepted Answer · 2014-02-06 20:44:27Z

0

Here is how I got it to work

  $filename="surface.txt"
 $fp = fopen($filename, "r");
 $content = fread($fp, filesize($filename));
 $lines = explode("\n", $content);
 for ($i=0; $i<$row; $i++){
 for ($j =0; $j<$col; $j++){

  $matrix[$i][$j] = $lines[$i*$col + $j];
 }
 }

answered Feb 6, 2014 at 20:44

user2791530

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Dharman · Accepted Answer · 2024-11-03 22:05:02Z

0

<?php

//asuming $row and $col are defined
//$row=5;
//$col=5;

$filename = "surface.txt";

$content = file_get_contents($filename);
$lines = explode("\n", $content);
foreach ($lines as $rowNum => $r) {
    $r = str_split($r);
    if ($rowNum + 1 > $row) {
        break;
    }
    if ($r === [""]) {
        continue;
    }
    while (count($r) > $col) {
        array_pop($r);
    }
    $matrix[] = $r;
}
var_dump($matrix);

edited Nov 3, 2024 at 22:05

Dharman♦

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answered Feb 6, 2014 at 13:58

chiliNUT

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7 Comments

user2791530 Over a year ago

After adding $lines=str_split($lines); my output is all NULL :(

chiliNUT Over a year ago

I assume the file is raw data, OP did not mention any characters in it not to process.

user2791530 Over a year ago

the text file has all token numbers.. I need to put it into a 2D array to be able to access each of the token.

chiliNUT Over a year ago

did my edit work? if you really don't wanna process all data, and only want to process $row number of rows and $col number of cols I can show you how to do that too

user2791530 Over a year ago

Could you please check and see if it works? any syntax errors?

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