sclass BWImageCategorizer {

  new L<BWImage> images;

  float allowedDistance = 0.1f; // allowed difference within category

  *() {}

  *(float *allowedDistance) {}

  int locateImage(BWImage img) {

    for i over images:

      if (bwDistance(images.get(i), img, allowedDistance) <= allowedDistance)

        ret i;

    ret -1;

  }

  int addImage(RGBImage img) { ret addImage(new BWImage(img)); }

  int addImage(BWImage img) {

    int i = locateImage(img);

    if (i >= 0) ret i;

    images.add(img);

    ret l(images)-1;

  }

  int numCategories() { ret l(images); }

  void clear() { images.clear(); }

  L<RGBImage> rgbImages() { ret bwImagesToRGB(images); }

  // find best fit regardless of distance

  // returns Pair<index, confidence>

  Pair<Int, Float> locateLax(BWImage img) {

    new Lowest<Int> l;

    for i over images:

      l.put(i, bwDistance(images.get(i), img));

    ret pair(or(l.get(), -1), 1f-l.floatScoreOr(1));

  }

}