带有循环的 Python 计数器/Prob

Question

I got 2 list of coordinates, X and Y. If we plot them, we would see a more or less circular trajectory. My objective is to count, the number of circle trajectory that is done.

The idea of the algorithm:

1..I calculate the average center of the trajectory

Center = (int(sum(X)/len(X)), int(sum(Y)/len(Y)))

Center will be X0 and Y0

2..K is the counter. I look where the point is, and everytime it get back in the south / west area, K += 1. Moreover, until i get out of this area, K doesn't stack up anymore.

        K = 0
        c = 0
        while c < len(X):
            if X[c] >= X0 and Y[c] >= Y0:
                c += 1
                continue
            elif X[c] < X0 and Y[c] >= Y0:
                c += 1
                continue
            elif X[c] >= X0 and Y[c] < Y0:
                c += 1
                continue
            else:
                K += 1
                # On saute les points suivants dans le même quart
                while X[c] < X0 and Y[c] < Y0:
                    c += 1

It works, but not if my final points are in this area, in which case, i get an out of range with the while X[c] < X0 and Y[x] < Y0.

I tried this code, that i found better, but i can't get it to work:

for c in range(len(X)):
                if X[c] >= X0 and Y[c] >= Y0:
                    continue
                elif X[c] < X0 and Y[c] >= Y0:
                    continue
                elif X[c] >= X0 and Y[c] < Y0:
                    continue
                else:
                    K += 1
                    while X[c] < X0 and Y[c] < Y0:
                        # Here i need a continue but on the for, not on the while...

Any help would be priceless.

Thanks !

Answer 1

I am hoping that I understood the problem correctly, What you are looking for is to break out of single loop in a nested loop? You can use an exception to return from inner loop

class Found(Exception): pass
for c in range(len(X)):
       try:
                if X[c] >= X0 and Y[c] >= Y0:
                    continue
                elif X[c] < X0 and Y[c] >= Y0:
                    continue
                elif X[c] >= X0 and Y[c] < Y0:
                    continue
                else:
                    K += 1
                    while X[c] < X0 and Y[c] < Y0:
                         #do whatever you want here               
                         raise Found  #raise exception when condition occurs
        except Found:
               print(K)

Answer 2

You can find below a solution, not really beautiful, but working. It checks where the last position is. If it's in the 1/4 of the circle currently being checked, it changes the checking area to the opposite 1/4.

if (X[len(X)-1] >= X0 and Y[len(X)-1] >= Y0) or (X[len(X)-1] < X0 and Y[len(X)-1] >= Y0) or (X[len(X)-1] >= X0 and Y[len(X)-1] < Y0):
            while c < len(X):
                if X[c] >= X0 and Y[c] >= Y0:
                    c += 1
                    continue
                elif X[c] < X0 and Y[c] >= Y0:
                    c += 1
                    continue
                elif X[c] >= X0 and Y[c] < Y0:
                    c += 1
                    continue
                else:
                    K += 1
                    # skip the following points in the same quarter
                    while X[c] < X0 and Y[c] < Y0:
                        c += 1
        else:
            while c < len(X):
                if X[c] <= X0 and Y[c] <= Y0:
                    c += 1
                    continue
                elif X[c] > X0 and Y[c] <= Y0:
                    c += 1
                    continue
                elif X[c] <= X0 and Y[c] > Y0:
                    c += 1
                    continue
                else:
                    K += 1
                    # skip the following points in the same quarter
                    while X[c] > X0 and Y[c] > Y0:
                        c += 1