Inline generator expressions with Cython
Besides any() and all(), Cython also has support for inline generator expressions in sum() now - and it’’s fast!
# CPython 2.6.5: timeit "sum(i for i in xrange(10000))" 1000 loops, best of 3: 584 usec per loop
# Cython 0.13-pre:
def range_sum_typed(int N):
cdef int result = sum(i for i in range(N))
return result
timeit "range_sum_typed(10000)"
100000 loops, best of 3: 2 usec per loop
Obviously a really stupid benchmark, but still - that’’s what I call a difference!
Here’’s another benchmark for looping over a fixed list of Python integers instead:
# CPython 2.6.5: timeit -s "r=range(10000)" "sum((i*i for i in r), 100)" 1000 loops, best of 3: 868 usec per loop
# Cython 0.13-pre:
def typed_sum_squares(seq, int start):
cdef long i, result
result = sum((i*i for i in seq), start)
return result
timeit -s "r=range(10000)" "typed_sum_squares(r, 100)"
10000 loops, best of 3: 49.9 usec per loop
Not exactly what I”d call “closer”. 