Convert CSV file data into transposed 2d array with the first row's (header) values used as first level keys

Question

I am trying to create a multidimensional array using CSV file so that for example:

"a","b","c"  
1,2,3  
4,5,6

would return as:

array(  
    'a' => array(1, 4),  
    'b' => array(2, 5),  
    'c' => array(3, 6),  
)

But the code I have:

<?php
function readCSV($csvFile) {
    $aryData = [];
    $header = NULL;
    $handle = fopen($csvFile, "r");
    if($handle){
        while (!feof($handle)){
            $aryCsvData = fgetcsv($handle);
            if(!is_array($aryCsvData)){
                continue;
            }
            if(is_null($header)){
                $header = $aryCsvData;
            } 
            elseif(is_array($header) && count($header) == count($aryCsvData)){
                $aryData[] = array_combine($header, $aryCsvData);
            }
        }
        fclose($handle);
    }
    return $aryData;
}

print_r(readCSV("Book1.csv"));
?>

Returns it as:

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

why while(!feof($handle)) is wrong

Barmar
– Barmar

2018-08-13 18:47:32 +00:00
Commented Aug 13, 2018 at 18:47 — Barmar
– Barmar, Commented Aug 13, 2018 at 18:47

Nigel Ren · Accepted Answer · 2018-08-13 18:55:58Z

0

Instead of building the end array as you go along. This code reads the header row before the loop, then just reads all of the data lines into another array. It then combines each element of the header array with the matching column from the data array (using array_column() and the position of the header element)...

function readCSV($csvFile) {
    $aryData = [];
    $output = [];
    $header = NULL;
    $handle = fopen($csvFile, "r");
    if($handle){
        $header = fgetcsv($handle);
        while ($aryData[] = fgetcsv($handle));
        foreach ( $header as $key=>$label) {
            $output[$label] = array_column($aryData, $key);
        }
        fclose($handle);
    }
    return $output;
}

answered Aug 13, 2018 at 18:55

Nigel Ren

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Barmar · Accepted Answer · 2018-08-13 18:56:21Z

0

Read the first row of the file and create the associative array with empty columns. Then read each remaining row and loop through it, pushing the values onto the column arrays.

<?php
function readCSV($csvFile) {
    $aryData = [];
    $handle = fopen($csvFile, "r");
    if($handle){
        $headerRow = fgetcsv($handle);
        if (!$headerRow) {
            return $aryData;
        }
        foreach ($headerRow as $colname) {
            $aryData[$colname] = [];
        }
        while ($aryCsvData = fgetcsv($handle)){
            foreach ($headerRow as $colname) {
                $aryData[$colname][] = each($aryCsvData);
            }
        }
        fclose($handle);
    }
    return $aryData;
}

answered Aug 13, 2018 at 18:56

Barmar

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