Writing to a CSV - column by column instead of row by row - php

Question

I'm familiar with creating a CSV, then adding lines to it by using functions like fputcsv, or manually with fwrite. IE:
fwrite($fh, $facility . "\r\n");
fwrite($fh, $s . " - " . $e . "\r\n");
fwrite($fh, "\r\n");
fwrite($fh, "\r\n");
foreach ($first_column as $f){
fwrite($fh, $f . "," . "\r\n");
}
My $first_column array looks something like:
$first_column = array(
'Chocolate Milk',
'White Milk',
'Orange Juice',
'Apple Juice',
);
It creates a file that looks similar to this:
West Middle School
5/1/2013 - 5/3/2013
Chocolate Milk,
White Milk,
Orange Juice,
Apple Juice,
I'd like to add data in the next field based on dates. The data will look similar to this:
$second column['05/01/2013'] = array(5,3,2,2);
$third column['05/02/2013'] = array(5,1,3,5);
I then can just loop through each date, and match up the values to the $first_column mapping.
Can this be done? Or will I have to write the data on a row by row basis like:
$data_row['chocolate milk'] = array(5,5,3,6);
$data_row['white milk'] = array(3,1,5,0);
My desired CSV would be something like this:
West Middle School
5/1/2013 - 5/3/2013
,5/1/2013,5/2/2013
Chocolate Milk,5,5
White Milk,3,1
Orange Juice,2,3
Apple Juice,2,5

Answer 1

You can have data in your program in column basis. But write them to file in this manner is not optimal. Better will be to create csv structure in memory and then store it in row order.
However, you can store them in col-by-col. Just write first collumn. Close file. Reopen file, load it line-by-line and append to end of each line second column. This create you new "line". Write it to new file.... and repeat this until done. This is fastest solution to programm, if you want to col-by-col aproach. Efficiency of this approach will be poor, of course.