We're are trying to get the direction of a projectile but we can't find out how

For example:

[1,1] will go SE

[1,-1] will go NE

[-1,-1] will go NW

and [-1,1] will go SW

we need an equation of some sort that will take the player pos and the mouse pos and find which direction the projectile needs to go.

Here is where we are plugging in the vectors:

def update(self):

    self.rect.x += self.vector[0]
    self.rect.y += self.vector[1]

Then we are blitting the projectile at the rects coords.