Example: running playlist based on tempo

[froggeric]

You have done such a great job with goofy, it is fantastic! I love it. I have been working on porting all my SmarterPlaylists and own python programs to Google Apps Script platform using Goofy, making some improvements in the process. I have recently finished porting quite a complex,, but useful program, and I thought sharing it here could benefit others,

The following script generates multiple running playlists. There are all based on a target tempo (180 steps per minute with a 15% deviation). Spotify tempo calculations can a bit misleading, and to get all the suitable tracks, I also need to consider half-tempos (or double depending on the target). The energy audio attribute is also taken into account, to avoid picking up tracks at the right tempo, but not good for pacing. The resulting tracks are also sorted by increasing tempo, to ensure a smooth running progression, and the half-tempos are taken into account. Finally, tracks can be taken and combined from multiple playlists.

// Running playlists
// Sources: merengue, cumbia, reggaeton
// filtered on bpm (including halved) and energy
function createRunningPlaylists() {

  let durationMax = 90;    // max duration in minutes of the final playlist
  let bpmTarget = 180;     // 180 BPM is the recemmended number of steps per minute for running
  let bpmDeviation = 0.15; // BPM range will be 15% of the target, centered around the target BPM
  let today = (new Date()).toISOString().split('T')[0];

  // Source playlists
  let tracksCumbia = FilterRunningPlaylist('<!>Cumbia [archive]', '1hSmpmZbgkoGpcIrCU9rpF', bpmTarget, bpmDeviation);
  let tracksMerengue = FilterRunningPlaylist('<!>Merengue [archive]', '0W2lVKgN2AbsFus2RIAiHz', bpmTarget, bpmDeviation);
  let tracksReggaeton = FilterRunningPlaylist('<!>Reggaeton [archive]', '1UoWJkPDZbNwuvNYrH6JRu', bpmTarget, bpmDeviation);
 
  // ► ¡Corre! ►
  let name = '► ¡Corre! ►';
  let id = '3ObKrWDdeEAcO7RxWRMItj';
  let description = "[DAILY REFRESH " + today + "] 90 minutes of latin songs for running, around the 180 BPM range (including halved BPM). Selected from my Cumbia, Merengue and Reggaeton playlists. Sorted by increasing tempo.";
  // Make a copy of the cumbia playlist as a starting point
  let tracks = Selector.sliceCopy(tracksCumbia);
  // Add the merengue and reggaeton playlists
  Combiner.push(tracks, tracksMerengue, tracksReggaeton);
  // Shuffle, extract duration, and save playlist
  SaveRunningPlaylist( name, id, tracks, description);

  // ► run: Cumbia ►
  name = '► run: Cumbia ►';
  id = '7ufkYNx8uyiHA1uDrH1ca3';
  description = "[DAILY REFRESH " + today + "] 90 minutes of cumbia songs for running, around the 180 BPM range. Sorted by increasing tempo."
  // Shuffle, extract duration, and save playlist
  SaveRunningPlaylist( name, id, tracksCumbia, description);

  // ► run: Merengue ►
  name = '► run: Merengue ►';
  id = '5CzTxbjBq7GYCyyPaaRmMY';
  description = "[DAILY REFRESH " + today + "] 90 minutes of merengue songs for running, around the 180 BPM range.  Sorted by increasing tempo."
  // Shuffle, extract duration, and save playlist
  SaveRunningPlaylist( name, id, tracksMerengue, description);

  // ► run: Reggaeton ►
  name = '► run: Reggaeton ►';
  id = '0Bul5uwXpAZsNQB3RgNlDE';
  description = "[DAILY REFRESH " + today + "] 90 minutes of reggaeton songs for running, around the 180 BPM range. Sorted by increasing tempo."
  // Shuffle, extract duration, and save playlist
  SaveRunningPlaylist( name, id, tracksReggaeton, description);


  function FilterRunningPlaylist( name, id, bpmTarget = 180, bpmDeviation = 0.15 ) {

    let bpmMargin = bpmTarget*bpmDeviation/2; // half percentage of BPM deviation to -/+ around the target
    let bpmMin = bpmTarget - bpmMargin;       // minimum BPM of tracks to keep
    let bpmMax = bpmTarget + bpmMargin;       // minimum BPM of tracks to keep

    // get source tracks
    let tracks = Source.getTracks([
      {
        name: name,
        id: id
      }]);
    let total = tracks.length;
  
    // Make a copy of the playlist for halved BPM filtering
    let halvedTracks = Selector.sliceCopy(tracks);

    // Filter the tracks based on tempo and energy
    // Add tempo information to tracks
    FilterByTempo( tracks, bpmMin, bpmMax, 1 );
    FilterByTempo( halvedTracks, bpmMin/2, bpmMax/2, 2 );

    let totalFullBPM = tracks.length;
    let totalHalfBPM = halvedTracks.length;
    
    // Combine both results, shuffle the tracks, and only keep up to a maximum duration
    Combiner.push(tracks, halvedTracks);
    let totalFiltered = tracks.length;

    Logger.log("Filtered " + totalFiltered + '/' + total + ' tracks (' + totalFullBPM + ' @ ' + bpmMin + '-' + bpmMax + ' bpm + ' + totalHalfBPM + ' @ ' + bpmMin/2 + '-' + bpmMax/2 + ' bpm) from ' + name);

    return tracks;
  }


  function FilterByTempo( tracks, bpmMin, bpmMax, multiplier = 1 ) {

    let energyMin = 0.4;  // minimum energy of tracks to keep
    let energyMax = 1.0;  // maximum energy of tracks to keep

    // Only keep tracks tracks within the desired BPM range
    // Only keep tracks with sufficient energy
    Filter.rangeTracks(tracks, {
      features: {
        tempo: { min: bpmMin, max: bpmMax },
        energy: { min: energyMin, max: energyMax }
      }
    });

    // Add tempo information to tracks
    // Since the audio features have alredy been queried during the filtering,
    // goofy keeps them in the cache, and we can retrieve the whole cache content
    let cache = getCachedTracks(tracks, { features: {} }).features;
    let cachedItems = Object.values(cache);

    // For efficiency, since we have a lot more in the cache than the tracklist,
    // we first iterate through all the cached items
    for (let x = 0; x < cachedItems.length; x++) {
      let item = cachedItems[x];
      let id = item.id;
      // Now we iterate the tracklist to find a matching track, if any
      for (let y = 0; y < tracks.length; y++) {
        // Check it the current cached item is a match for the current track
        if ( tracks[y].id == id ) {
          // Save the tempo (potentially modified) to the track properties
          let tempo = item.tempo * multiplier;
          tracks[y].tempo = tempo;
          // Logger.log( id + ' = '+ tracks[y].id + ' : ' + tempo);
        }
      }
    }
  }


  function SaveRunningPlaylist( name, id, tracks, description) {
 
    // dedup and shuffle tracks, before only keeping up to the maximum duration
    Filter.dedupTracks(tracks);
    let total = tracks.length;
    Order.shuffle(tracks);
    Selector.keepNoLongerThan(tracks, durationMax+1);
    let saved = tracks.length;

    Logger.log("Creating custom playlist: " + name + ' (kept ' + saved + '/' + total + ' tracks)');

    // Sort by increasing tempo
    tracks.sort((x, y) => {
        return x.tempo - y.tempo;
    });

    // for (let y = 0; y < tracks.length; y++) {
    //   Logger.log( tracks[y].tempo + ' ' + tracks[y].name);
    // }

    // Save playlist, without modifying the cover 
    Playlist.saveWithReplace({
      id: id,
      name: name,
      tracks: tracks,
      description: description,
      public: true
    });

  }

}

If you are interesting in checking out the result, here is my main running playlist on spotify, combining all 3 genres:
► ¡Corre! ► playlist on Spotify

[Bondian]

Полезная вещь! Спасибо! Обязательно воспользуюсь на досуге