Speeding up date / time comparison with Cython

Question

I am trying to speed up comparison between dates using Cython when an array of numpy datetimes (or details sufficient to create datetimes) is passed. To get started, I tried to understand how Cython will speed up the comparison of integers.

testArrayInt = np.load("testArray.npy")

Python Method:

def processInt(array):
    compareSuccess = 0#number that is greater than
    testValue = 1#value to compare against
    for counter in range(testArrayInt.shape[0]):
        if testValue > testArrayInt[counter]:
            compareSuccess+=1
    print compareSuccess

Cython Method:

def processInt(np.ndarray[np.int_t,ndim=1] array):
    cdef int rows = array.shape[0]
    cdef int counter = 0
    cdef int compareSuccess = 0
    for counter in range(rows):
        if testInt > array[counter]:
            compareSuccess = compareSuccess+1
    print compareSuccess

Comparing time with an array of numpy strings of 1,000,000:

Python: 0.204969 seconds
Cython: 0.000826 seconds
Speedup: 250 times approx.

Repeating the same exercise with dates: Since cython did not accept the datetime array, I split and sent the array from year, month, and day for both methods.

testArrayDateTime = np.load("testArrayDateTime.npy")

Python Code:

def processDateTime(array):
    compareSuccess = 0
    d = datetime(2009,1,1)#test datetime used to compare
    rows = array.shape[0]
    for counter in range(rows):
        dTest = datetime(array[counter][0],array[counter][1],array[counter][2])
        if d>dTest:
            compareSuccess+=1
    print compareSuccess

Cython Code:

from cpython.datetime cimport date

def processDateTime(np.ndarray[np.int_t, ndim=2] array):
    cdef int compareSuccess = 0
    cdef int rows = avlDates.shape[0]
    cdef int counter = 0
    for counter in range(rows):
        dTest = date(array[counter,0],array[counter,1],array[counter,2])
        if dTest>d:
            compareSuccess=compareSuccess+1
    print compareSuccess

Performance:

Python: 0.865261 seconds
Cython: 0.162297 seconds
Speedup: 5 times approx. 

Why is the speed so low? And what is a possible way to increase this?

Answer 1

date . , , , , , .

np.datetime64 , , .