[RESOLVED] HOW CAN I SORT FLATFILE DATA BY TWO FIELDS?

DaleRobbins

Hi folks, I have only a elementary level of experience with PHP, and could use some assistance in sorting this flat file data (Sql is not available for this application). I use this script (see below) to perform an alphabetical sort on a pipe delimited textfile of music genres (field 0). HOWEVER, I also need to do a 2nd sort on the music titles too (field 1). In other words, I want all the genres to be alpha sorted, and then all the titles beneath the genres, sorted alphabetically too. See the sample RAW data, and the sample SORTED data that I'm trying to achieve. (The remaining three fields don't need sorted.) Any help will be gratefully appreciated!

genre|title|artist|time|url


<?php

$rows = array();
$resultstring = "";
$file = file("musiclist.txt");

foreach($file as $key => $val){
    // explode by comma
    $rowarray = explode("|",$val);

// get only the second column
$rows[] = $rowarray[0];
}

// sort by names
asort($rows);

// put the result with the help of the key to output array
foreach($rows as $key => $val){
    $resultstring .= trim($file[$key]) . "\r\n";
}

// show the result
echo $resultstring;

//file_put_contents("musiclist.txt", $resultstring);

?>

dalecosp

DaleRobbins wrote:
//explode by comma

You're actually exploding by pipe ... 😉

// get only the second column 
    $rows[] = $rowarray[0];

That would get the FIRST "column", right?

Is this a "set list" of categories, or do you need to parse the file for categories first?

Here's how I did that:

<?php

$data = file("./songs.txt");

$genre_list = array();

foreach ($data as $d) {

$ex = explode("|", $d);
$genre_list[] = $ex[0];

}

$genre_list = array_unique($genre_list);

sort($genre_list);

print_r($genre_list);

At this point, you'd probably create an array for each genre, than parse through $data again (might have to call rewind()?) and assign songs that matched to each array in turn ...

DaleRobbins

Yes, I would need to parse sort the categories first, then sort the titles. I'm afraid it's a little beyond my skills to figure out how to rewind, etc.

dalecosp

Well, I'm not sure you should be learning from me, as there are people here who could probably one-line this (and, ironically enough, probably by using the [man]array_multisort[/man] function I use twice below). Forgive me, as it's 10 minutes 'til quitting time in this TZ and I'm brain dead (and not too "brain alive" even at 8 AM) ...

But here ya go:

<?php

//Init
$c             = 0; //counter
$end_character = ''; //if you need a special line ending
$genre_list    =
$big_list      = array();
$file          = "./songs.txt"; //name of datafile


// get data
$data          = file($file);

//create genre_list, eliminate duplicate entries, sort
foreach ($data as $d) {

$ex = explode("|", $d);
$genre_list[] = $ex[0];
}

$genre_list = array_unique($genre_list);
sort($genre_list);

// rewind not needed. Read the other details into members of the $big_list 
//array (keyed by genre), then sort it with array_multisort to preserve text keys

foreach ($data as $d) {

    $ex      = explode("|", $d);
    $genre = $ex[0];

    $big_list[$genre][$c]['title']    = $ex[1];
    $big_list[$genre][$c]['artist']  = $ex[2];
    $big_list[$genre][$c]['timing'] = $ex[3];
    $big_list[$genre][$c]['url']      = $ex[4];
    $c++;
}

// at this point you could "print_r($big_list)" to see the data structure for learning...

array_multisort($big_list); //sort, keeping associative keys

//OUTPUT

foreach ($genre_list as $genre) {

   array_multisort($big_list[$genre]); //ditto

   foreach ($big_list[$genre] as $song) {

  echo $genre . "|"
     . $song['title'] . "|"
     . $song['artist'] . "|"
     . $song['timing'] . "|"
     . $song['url']    . $end_character; //PHP_EOL not needed because file() kept the newlines in the data.  HTML <br>?

   }
}

Warning: this will probably not scale real well --- if you have a large data file I'd be cautious 😉

Weedpacket

Using [man]fgetcsv[/man] (specifying a pipe for the delimiter) could also be used for the reading.

You can build the [font=monospace]$genre_list[/font] and [font=monospace]$big_list[/font] of dalecosp's sample concurrently, since you don't need the completed genre list until you've finished reading the file (so, no rewinding). In fact, you can build [font=monospace]$genre_list[/font] from the contents of [font=monospace]$big_list[/font]; if you're using a version of PHP >= 5.5 then [font=monospace]$genre_list = array_unique(array_column($big_list, 0));[/font] will do that.

...Ah, okay.

array_multisort($big_list, SORT_ASC, SORT_STRING, array_column($big_list, 1)); // Sort by title
$genre_list = array_fill_keys(array_unique(array_column($big_list, 0)), []); // Genre list
ksort($genre_list); // Have to do this sometime, might as well be now.
foreach($big_list as $track)
{
    $genre_list[$track[0]][] = $track;
}

(PS: [noparse]Mysite.com[/noparse] is a thing; Example.com exists for that sort of usage.)

(PPS: If it is a large file, then rewinding a file handle is a matter of calling [man]rewind[/man] between one read-through and the next. But if it's that large then there are other considerations, like the fact you'll need to write stuff out before you've read everything. Since you happen to want to sort the file by its first and second columns, you can just throw the whole thing through a command-line sort(1) without any special effort and it will come out right.)

Weedpacket

PPPS: If you're not actually grouping by genre, but just sorting by it, then it's a matter of reading the file into [font=monospace]$big_list[/font] and

// Sort $big_list by genre, then title.
array_multisort($big_list, SORT_ASC, SORT_STRING, array_column($big_list, 0), SORT_ASC, SORT_STRING, array_column($big_list, 1));

laserlight

DaleRobbins wrote:
sorting this flat file data (Sql is not available for this application)

Out of curiosity, but why is that so? I understand that perhaps a fully featured RDMS like MySQL or PostgreSQL might not be available, or you may wish to eschew using them for reasons of configuration and such, but SQLite is likely to be available and is generally suitable as a zero-configuration flat file replacement.

DaleRobbins

Thank you for your help, my friends! Dalecosp and WeedPacket, you especially gave me the insight I needed to make my needed adjustments. THANKS AGAIN!

DaleRobbins

Thank you for your help my friend!

DaleRobbins

Thanks to all!