列表索引超出python 2.7中的范围

Question

I need to create a program in python using fourier transform. It says: list index out of range,and I don;t understand why. The error is at these lines:

Feven = fft([x[i] for i in xrange(0, n, 2)],n/2)
Fodd = fft([x[i] for i in xrange(1, n, 2)],n/2)

Answer 1

Have you tried separating the the list compilation from function call to find out the location the exception is thrown?

# assuming n <= len(x)
even = [x[i] for i in xrange(0, n, 2)]
Feven = fft(even,n/2)

You could also use slicing to get every second element in list:

even = x[::2]
odd = x[1::2]