python for loop not executing enough times

Question

I am trying to make a game in pygame. The program involves looping through an array of objects, and determining whether they collide with another object. However, when I run the for loop it doesn't execute as many times as there is objects in the list.

print(f"Length of array: {str(len(Crate.Crates))}")
counter = 0
   for crate in Crate.Crates:
       counter += 1
       if crate.colide and crate.rect.colliderect(self.explosionRect):
           crate.hitByBall()
print(f"loop has executed {str(counter)} times")

The output I get after running this code is the following:

Length of array: 25
loop has executed 23 times

Here is the GitHub repository where you can find the entire code: https://github.com/Mateusz9/game (the code fragment mentioned above is located game/crates/Bomb/crate.py)

What does hitByBall do? Does it remove objects for the list? If so, iterate a copy tf the list for crate in Crate.Crates[:]: — Rabbid76
– Rabbid76, Commented Apr 17, 2021 at 12:39
thanks @Rabbid76. Iterating over the copy of the list works perfectly — Mateusz Gge
– Mateusz Gge, Commented Apr 17, 2021 at 12:51

Rabbid76 · Accepted Answer · 2021-04-17 12:53:16Z

1

If the method crate.hitByBall() method removes objects from the list, you must iterate over a copy of the list (see also How to remove items from a list while iterating?):

~~for crate in Crate.Crates:~~

for crate in Crate.Crates[:]:

answered Apr 17, 2021 at 12:53

Rabbid76

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