PHP insert array values to csv column

Question

I have a large (size ~ 12k) 2D array of data like below and I want to insert these data into a csv file.

$data = array
(
    'a' => array
    (
        0 => 111,
        1 => 222,
        2 => 333,
        3 => 444,
    ),
    'b' => array
    (
        0 => 555,
        1 => 666,
        2 => 777,
        3 => 888,
    ),
    'c' => array
    (
        0 => 999,
        1 => 000,
        2 => 111,
        3 => 222,
    ),
);

Here 'a', 'b', and 'c' would be the CSV header row, and corresponding array values should be inserted like below:-

a	b	c
111	555	999
222	666	000
333	777	111
444	888	222

I know fputcsv can be used to insert the data but it insert the array values as a row in the csv but in my case I want to insert the array values to a csv column.

Is there any simpler way to insert all the array values to the csv columns like above table?

Related: [Access, transpose, and join data from a .csv file](https://stackoverflow.com/q/18722015/2943403) — mickmackusa, Apr 07 '23 at 11:51

Fravadona · Answer 1 · 2023-04-07T13:07:07.517

2

There exists an array_column function that might be of help:

$out = fopen('php://stdout', 'w');

# output the CSV header
fputcsv($out, array_keys($data));

# output the CSV records
foreach ( array_keys( $data[ array_key_first($data) ] ) as $column_key) {
     fputcsv($out, array_column($data, $column_key));
}

output:

a,b,c
111,555,999
222,666,0
333,777,111
444,888,222

edited Apr 07 '23 at 13:07

answered Apr 06 '23 at 10:35

Fravadona

13,917
1
23
35

1

Nice use of array_column. Is there any particular reason for using a by-reference loop (`as &$column_key` rather than just `as $column_key`)? – IMSoP Apr 06 '23 at 11:13
No, there isn't any good reason; I fixed it – Fravadona Apr 06 '23 at 11:16

user2342558 · Accepted Answer · 2023-04-06T10:36:04.223

Assuming that each sub-array contains the same count of values, you can achieve your goal with just a few lines of code:

use array_keys to get all the column names from your array
iterate each sub-array to compose the single row, assuming that each value of that row is in the same array index position

$data = array
(
    'a' => array
    (
        0 => 111,
        1 => 222,
        2 => 333,
        3 => 444,
    ),
    'b' => array
    (
        0 => 555,
        1 => 666,
        2 => 777,
        3 => 888,
    ),
    'c' => array
    (
        0 => 999,
        1 => 000,
        2 => 111,
        3 => 222,
    ),
);
    
$fp = fopen('file.csv', 'w');

// headers
fputcsv($fp, array_keys($data));

// rows contents
for($i = 0; $i<count(current($data)); $i++) {
    $row = [];
    foreach($data as $k => $v) {
        $row[] = $v[$i];
    }
    fputcsv($fp, $row);
}
    
fclose($fp);

Try it online on https://onlinephp.io/c/735bc, with this results:

a,b,c
111,555,999
222,666,0
333,777,111
444,888,222

In the official documentation you can find many other useful array functions.

score 1 · Answer 3 · answered Apr 06 '23 at 10:29

Since CSV files are fundamentally written row by row, you'll need to:

Determine how many rows you want to generate
Loop that many times, picking one item for each column

Assuming all your sub-arrays have the same number of keys, you could set up this way:

$lastRowNumber = array_key_last($data['a']);
$columns = array_keys($data);

And then your loop would look like this:

for ( $rowNumber = 0; $rowNumber <= $lastRowNumber; $rowNumber++ ) {
    $csvRow = [];
    foreach ( $columns as $columnKey ) {
        $csvRow[] = $data[$columnKey][$rowNumber];
    }
    fputcsv($outputFileHandle, $csvRow);
}

Demo echoing the data rather than writing with fputcsv: https://3v4l.org/P5rtU

Alternatively, you could loop using a list of row keys, rather than assuming they're sequentially numbered. For instance, taking the keys from the first sub-array:

$columnKeys = array_keys($data);
$rowKeys = array_keys($data[$columnKeys[0]]);

Then use foreach instead of for:

foreach ( $rowKeys as $rowKey ) {
    $csvRow = [];
    foreach ( $columnKeys as $columnKey ) {
        $csvRow[] = $data[$columnKey][$rowKey];
    }
    echo implode(',', $csvRow), PHP_EOL;
}

I was also thinking to kind of transform the array and then insert with `fputcsv`. I tried @user2342558 answer and it is working fine for me. Although, thanks for your response :) — Arpit Jain, Apr 06 '23 at 10:42

PHP insert array values to csv column

3 Answers3