float object has no attribute __getitem__

问题:

This is the error I'm getting from this function:

TypeError: 'float' object has no attribute '__getitem__'

The self.target is just an tuple and self.x and self.y are ints, I don't know what I've done wrong.

class Robot(object):
def __init__(self):
    global WIDTH
    global HEIGHT
    global BACKGROUND
    self.speed = random.randint(0,8)
    self.size = 5
    self.counter = 0
    self.direction = "n"
    self.target = (0,0)
    self.directions = ["n","ne","e","se","s","sw","w","nw","stop"]
    self.distance_to_cords = {}
    self.target_cords = []

    self.direction_movementsy = {"n": -1,
                                "ne" : -1,
                                "e" : 0,
                                "se" : 1,
                                "s": 1,
                                "sw": 1,
                                "w": 0,
                                "nw": -1}

    self.direction_movementsx = {"n": 0,
                                "ne" : 1,
                                "e" : 1,
                                "se" : 1,
                                "s": 0,
                                "sw": -1,
                                "w": -1,
                                "nw": -1}







    self.x = random.randint(0,WIDTH)
    self.y = random.randint(0,HEIGHT)
    self.colour = RED

def draw(self):
    pygame.draw.polygon(DISPLAYSURF,self.colour,((self.x,self.y),(self.x,self.y + self.size ),(self.x + self.size,self.y + self.size),(self.x + self.size,self.y)))
    pygame.display.update()

def undraw(self):
    pygame.draw.polygon(DISPLAYSURF,BACKGROUND,((self.x,self.y),(self.x,self.y + self.size ),(self.x + self.size,self.y + self.size),(self.x + self.size,self.y)))
    pygame.display.update()

def direction_decider(self):
    #x stuff

    #w
    if self.target[0] < self.x:
        question1 = True
    else:
        question1 = False

    #e
    if self.target[0] > self.x:
        question2 = True
    else:
        question2 = False


    #n
    if self.target[0] < self.y: 
        question3 = True
    else:
        question3 = False

    #s
    if self.target[0] > self.y:
        question4 = True
    else:
        question4 = False


    answer = (question1, question2, question3, question4)


    lookup_which_direct = { (True,False,False,False):"w",
                            (False,True,False,False):"e",
                            (False,False,True,False):"n",
                            (False,False,False,True):"s",
                            (True,False,True,False):"nw",
                            (True,False,False,True):"sw",
                            (False,True,True,False):"ne",
                            (False,True,False,True):"se"}

    cheese =lookup_which_direct[answer]
    print cheese












def dist_calc(self):
    for p in plant_list:
        x_dist = self.x - p.x
        y_dist = self.y - p.y
        total_dist = (y_dist**2 +x_dist**2)**0.5
        self.distance_to_cords[total_dist] = (p.x,p.y)
    ordering_list = self.distance_to_cords.keys()
    ordering_list = sorted(ordering_list)
    self.target = ordering_list[0]
    self.target_cords = self.distance_to_cords[self.target]

回答1:

You set self.target to a float in dist_calc:

for p in plant_list:
    x_dist = self.x - p.x
    y_dist = self.y - p.y
    total_dist = (y_dist**2 +x_dist**2)**0.5
    self.distance_to_cords[total_dist] = (p.x,p.y)
ordering_list = self.distance_to_cords.keys()
ordering_list = sorted(ordering_list)
self.target = ordering_list[0]

Here ordering_list is a sequence of floating point values (the total_dist values), and you set self.target to the lowest value of these (you could have used min(self.distance_to_cords) there instead of sorting).

Perhaps you meant to set it to self.distance_to_cords[min(self.distance_to_cords)] instead?

回答2:

self.target has become a float somehow.

Perhaps something like self.target = self.target[0] happened somewhere in your code?

Either that, or self.target = some_variable_that_is_a_float

回答3:

total_dist = (y_dist**2 +x_dist**2)**0.5

This will be a float for most integer values of x_dist and y_dist.

self.distance_to_cords[total_dist] = (p.x,p.y)

Now self.distance_to_cords has a probable float key.

ordering_list = self.distance_to_cords.keys()
ordering_list = sorted(ordering_list)

Now ordering_list is a list of mixed floats and (occasionally) ints.

self.target = ordering_list[0]

Now self.target is probably a float, which means that your direction_decider would likely raise the exception you stated if called after your code at the bottom runs.