import numpy as np                                    
import itertools as it                                
import timeit                                         

def use_list(c):
    return np.array(list(c), dtype=np.complex64)

def use_tuple(c):
    return np.array(tuple(c), dtype=np.complex64)

def use_fromiter(x, length, c):
    count = len(x) ** length
    base_dtype = '<c8' # 64bit (i.e. 32bit native) complex
    dtype = ','.join(length*[base_dtype])

    data = np.fromiter(c, dtype=dtype, count=count)
    data = data.view(base_dtype).reshape((-1, length))

    return data

length = 9
x = [1,-1,np.complex(0,1), np.complex(0,-1)]

if __name__ == '__main__':
    t1 = timeit.timeit('use_fromiter(x, length, it.product(x, repeat=length))',
            setup='from __main__ import use_fromiter, length, x, it', number=1)
    t2 = timeit.timeit('use_list(it.product(x, repeat=length))',
            setup='from __main__ import use_list, length, x, it', number=1)
    t3 = timeit.timeit('use_tuple(it.product(x, repeat=length))',
            setup='from __main__ import use_tuple, length, x, it', number=1)

    print 'Times using a repeat of', length, ':'
    print 'Time using np.fromiter', t1, 's'
    print 'Time using lists', t2, 's'
    print 'Time using tuples', t3, 's'