I am working on a image search algorithm that finds certain shapes of certain colors; to save time I only register half of the shape's perimeter in 2 distinct sets, one for the rows and one for the columns used by the shape. The idea is that whenever I find a point which has the target color, I then check if this point's row and column are in a master set (which have both the previous sets); if they are I skip it, if they are not then I initialize 2 recursive fuctions that register the first row and the first column of the shape.
Since it's for a school project, my images are specially tailored
and the code would be
for y in range(height):
for x in range(width):
if img[y][x] == target:
if y in master_set and x in master_set:
continue
else:
row = set()
column = set()
flood_fillv2_y(img,x,y,target,column)
flood_fillv2_x(img,x,y,target,row)
row=frozenset(row)
column=frozenset(column)
master_set.add(row)
master_set.add(column)
The idea then is to check the len of master_set to see how many shapes I have, but as I said what I get is that y and x are never in the master set so it keeps doing it for all points of the shape, resulting in a wrong number.
It's hard to give a good answer without seeing the whole code, but I can give a guess:
master_set.add(row) literally adds the frozenset row to the master_set, but you probably want all elements from the set to be added to master_set. Take a look at the update() method of sets.
Does this help?