def register_scalar_cfunc(con, func):
pyfunc = func.pyfunc
narg = len(inspect.getargspec(pyfunc).args)
register_scalar_function(
con, pyfunc.__name__.encode('utf8'), narg, func.address
)
return c * exp(-0.5 * ((x - mu) / sigma) ** 2.0)
def oldnormal(x, mu, sigma):
c = 1.0 / (sigma * sqrt(2.0 * pi))
return c * exp(-0.5 * ((x - mu) / sigma) ** 2.0)
con = sqlite3.connect(':memory:')
con.execute('CREATE TABLE t (random_numbers DOUBLE PRECISION)')
random_numbers = [
(random.random(),) for _ in range(50000)
]
con.executemany('INSERT INTO t VALUES (?)', random_numbers)
# new way of registering C functions
register_scalar_function(con, b'normal', 3, normal.address)
# old way
con.create_function('oldnormal', 3, oldnormal)
query1 = 'select normal(random_numbers, 0.0, 1.0) as sine from t'
query2 = 'select oldnormal(random_numbers, 0.0, 1.0) as oldsine from t'
start1 = time.time()
exe1 = con.execute(query1)
result1 = list(exe1)
t1 = time.time() - start1
start2 = time.time()
exe2 = con.execute(query2)
result2 = list(exe2)
t2 = time.time() - start2
