Drag only one sprite in a group with the mouse - python-3.x

Question

The problem that I cannot figure how to sort is that when I drag a piece over another the second piece also is dragged along with the first. I have tried several ways to limit the mouse selection to one piece at at time, but all have failed. Can anyone help - no doubt there is a simple way! The code shorn of all my failed attempts follows:
# In main loop:
# Watch for keyboard and mouse events
for event in pygame.event.get():
if event.type == pygame.MOUSEBUTTONDOWN:
mouse_held = True
if event.type == pygame.MOUSEBUTTONUP:
mouse_held = False
# Update pieces that are in a sprite.Group()
pieces.update(mouse_held)
# In sprite class:
def update(self, mouse_held):
if mouse_held == True:
self.mouse_coordinates = pygame.mouse.get_pos()
if self.rect.collidepoint(self.mouse_coordinates) == True:
self.rect.centerx = self.mouse_coordinates[0]
self.rect.centery = self.mouse_coordinates[1]

Answer 1

Your question is fairly difficult but by doing all of this you should be able t achieve what you want.
You should change your sprite class to have a new variable of type int named depth (the higher the value the 'deeper' it is).
Considering you have a list of all the sprite objects you want to check for clicks called spriteList you should add this:
from operator import attrgetter
then change these lines:
if event.type == pygame.MOUSEBUTTONDOWN:
mouse_held = True
to:
if event.type == pygame.MOUSEBUTTONDOWN:
sprites = []
for sprite in spriteList:
if sprite.rect.collidepoint(event.pos) == True:
sprites.append(sprite)
active = min(lists, key=attrgetter('depth'))
mouse_held = True
You should replace the sprite's update function to:
def update(self):
self.mouse_coordinates = pygame.mouse.get_pos()
if self.rect.collidepoint(self.mouse_coordinates) == True:
self.rect.centerx = self.mouse_coordinates[0]
self.rect.centery = self.mouse_coordinates[1]
And finally when you want to update the sprite's position simply type:
if mouse_held:
active.update()