Try-except, IndexError, Alternatives to solve the error

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I have a college job to do, in a way I finished it, but with some gambiarras that I wanted to straighten out and leave the code less confusing and etc.

How the program works:

Basically it creates a 600x400 screen with a% w of% number of balls (this number is passed by the function of creating the balls) by walking through the window, when they hit the edges they take another path so that they always remain on the screen .

Explanation of functions:

  • x : Places the information as criaBola , tag , x and vertical / horizontal acceleration;

  • y : When the program starts, it spreads the balls randomly across the screen, throughout the program this function is used to make the balls walk on the screen;

  • criaBolas : Deletes the ball from the screen, this function is used both to make balls so much to 'pop' them;

  • verificaBolasArea : This is the heart of the program, causes the balls to change direction, indexes the other functions, etc.

Part I need help with:

In the removeBola function I needed to put a try-except for moveBola , what happened was when I started the program everything worked perfectly, I clicked on some balls and they were bursting like but when it came to the last ball the program gave " IndexError: list index out of range "; this mistake also happened sometimes with the other balls without being the last one. This was the only way I could make the program run without making a mistake, but I wanted to know if there are more alternatives to solving this kind of problem. 

from Tkinter import *
import random, time

largura = 600
altura = 400
diametro = 50
bola = ['', 0, 0, 0, 0]
bolas = []



def randPos():
    pos = [0,0]
    pos[0] = random.randint(1, (largura - diametro))
    pos[1] = random.randint(1, (altura - diametro))
    return pos


def randCor():
    R = random.randint(100, 255)
    G = random.randint(100, 255)
    B = random.randint(100, 255)
    cor = '#%02x%02x%02x' % (R,G,B)
    return cor


def criaBola(id, novaBola):
    if novaBola == True:
        posr = randPos()
        bolas[id][1] = posr[0]
        bolas[id][2] = posr[1]
    tela.create_oval(bolas[id][1], bolas[id][2], bolas[id][1] + diametro, bolas[id][2] + diametro, fill=randCor(), tags=bolas[id][0])
    tela.update()
    print 'bola[index:{}]'.format(bolas.index(bolas[id])),bolas[id][0], randCor(), "POS: X:{} Y:{}".format(bolas[id][1], bolas[id][2])

def criaBolas(quantidade):
    for n in range(quantidade):
        print "CRIA BOLAS INDICE N ", n
        bola[0] = ('bola{}'.format(n))
        bola[3] = 10
        bola[4] = 10
        bolas.append(bola[:])
        print bolas
        criaBola(n, True)
    print(bolas)

def removeBola(idBolaList, idBolaTela):
    print "REMOVENDO BOLA[{}]".format(idBolaTela)
    print type(idBolaList)
    if idBolaList == 999:
        print 'REMOVENDO BOLA PARA ATUALIZACAO DE COORDENADAS'
    else:
        print "PRINTANDO BOLA A SER APAGADA IDBOLALIST", idBolaList, idBolaTela
        bolas.pop(idBolaList)
    tela.delete(idBolaTela)

t = Tk()
tela = Canvas(t, width=largura, height=altura)
tela.pack()

def verificaBolasArea(px1, py1):
    for ii in range(len(bolas)):
        if (bolas[ii][1] <= px1) and (px1 <= (bolas[ii][1]+diametro)) and (bolas[ii][2] <= py1) and (py1 <= (bolas[ii][2] + diametro)):
            print 'O mouse clicou dentro da bola\nA bola[{}] esta nas coordenadas ({},{}) - (X,Y)'.format(bolas[ii][0],bolas[ii][1], bolas[ii][2])
            r = [bolas.index(bolas[ii]), bolas[ii][0]]
            return r
        else:
            print 'bola nao encontrada'

def motion(event):
    print 'tamanho lista:',len(bolas)
    mx, my = event.x, event.y
    r = verificaBolasArea(mx, my)
    removeBola(r[0], r[1])
    print "--->uma bola foi removida", bolas
    print('{}, {}'.format(mx, my))
t.bind('<ButtonRelease-1>', motion)

def encerra(event):
    t.destroy()
t.bind('<ButtonRelease-3>', encerra)


def attPos(id):
    print "ATTPOS ID PASSADO ",id, bolas[id][0]
    print bolas
    bolas[id][1] += bolas[id][3]
    bolas[id][2] += bolas[id][4]

def moveBola(idBola = []):
    i=0
    while i>-1:
        try:
            while i<=len(bolas):
                print "WHILE I MOVE BOLAS:" ,i
                index = idBola.index(idBola[i])
                if ((bolas[i][1]+diametro) > largura) or (bolas[i][1] < 0):
                    bolas[i][3] *= -1
                if ((bolas[i][2]+diametro) > altura) or (bolas[i][2] < 0):
                    bolas[i][4] *= -1
                time.sleep(0.0299)
                tela.update()
                print "******************",index
                print len(bolas), bolas, index
                removeBola(999, idBola[i][0])
                attPos(index)
                criaBola(index, False)
                i+=1
                if i == len(bolas):
                    i=0
        except IndexError:
            if len(bolas) <= 0:
                i=-1
                tela.create_text(largura / 2, altura /2, text="PARANBENS! VOCE ESTOUROU TODAS AS BOLAS.\nClique com o botao direito do mouse para fechar o programa.", font=("Arial Black", "12"), tags='Fim', fill='red')
            else:
                i=0
            print len(bolas)*100

criaBolas(10)
moveBola(bolas)

t.mainloop()
    
asked by anonymous 23.06.2018 / 05:55

1 answer

0

The len returns a value that starts from 1, not 0. However, the count of positions starts from 0. 

while i<=len(bolas):

Let's assume that len(bolas) equals 10: The positions of the balls are 0 to 9, which closes 10 numbers (len value), hi starts at 0 and goes up to 10 (because while i<=len(bolas) ), however, the array does not go to position 10, but until to 9.

I think that changing while i<=len(bolas): by while i<len(bolas): will solve your problem, so you do not need to try / except.

    
25.06.2018 / 16:50
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