sclass FaceDataSet {

  S csvSnippetID = #1032472;

  // by imageURL

  new Map<S, Entry> entryMap;

  new L<Entry> entries;

  class Entry {

    S imageURL;

    File imageFile;

    new Set<DoubleRect> facePositions;

    int w, h;

    *(S *imageURL) {

      imageFile = downloadImage(imageURL);

    }

    BufferedImage image() {

      var img = loadImage2(imageFile);

      if (img == null) print(imageFile + " not found");

      else {

        w = img.getWidth();

        h = img.getHeight();

      }

      ret img;

    }

    BufferedImage markedImage(int width default w()) {

      var img = scaleToWidth(image(), width);

      int height = img.getHeight();

      for (var face : facePositions) {

        Rect r = scaleRect_floor(face, width, height);

        drawBox(img, r, Color.red, 0.5);

      }

      ret img;

    }

    int w() { if (w == 0) image(); ret w; }

    int h() { if (h == 0) image(); ret h; }

  }

  File imagesDir() { ret javaxCachesDir("Google Face Data Set"); }

  File downloadImage(S url) {

    File file = newFile(imagesDir(), md5FileName(url) + fileExtension(url));

    if (file.length() == 0) null;

    if (!file.exists()) try {

      loadBinaryPageToFile(url, file);

    } catch e {

      if (containsExceptionOfType FileNotFoundException(e))

        // as a warning for future generations!

        saveBinaryFile(file, new byte[0]);

    }

    ret file.exists() ? file : null;

  }

  void load {

    for (LS row : parseExtendedCSV_iterator(loadSnippet(csvSnippetID))) {

      for n to 3: pcall {

        int i = n*5;

        S imageURL = convertHttpToHttps(row.get(i++));

        Entry e = entryMap.get(imageURL);

        if (e == null) {

          e = new Entry(imageURL);

          if (e.imageFile == null) continue with print("Skipping " + e.imageURL);

          entryMap.put(imageURL, e);

          entries.add(e);

        }

        e.facePositions.add(doubleRectFromPoints(

          parseDouble(row.get(i)),   // left column  (x1)

          parseDouble(row.get(i+2)), // top row      (y1)

          parseDouble(row.get(i+1)), // right column (x2)

          parseDouble(row.get(i+3)), // bottom row   (y2)

        ));

      }

    }

    print("Have " + nEntries(entries));

  }

}

/* Row begins: 

URL of image1 (string)

Top-left column of the face bounding box in image1 normalized by width (float)

Bottom-right column of the face bounding box in image1 normalized by width (float)

Top-left row of the face bounding box in image1 normalized by height (float)

Bottom-right row of the face bounding box in image1 normalized by height (float)

*/