A timing script for SPy SpyFile read methods with and without memmaps

memmap_speedups.py

# Timing tests for SpyFile read_ methods

from spectral import *

def create_files(src='av920612_NS_line.lan'):
    img = open_image(src)
    envi.save_image('bilfile.hdr', img, interleave='bil')
    envi.save_image('bipfile.hdr', img, interleave='bip')
    envi.save_image('bsqfile.hdr', img, interleave='bsq')

def timed(func):
    '''A timer for FileTimer read methods.'''
    import time
    def wrapped(*args):
        # Replace file name with associated SpyFile object
        args = [args[0]] + [open_image(args[1])] + list(args[2:])
        t = time.time()
        func(*args)
        return time.time() - t
    return wrapped

class FileTimer:

    @timed
    def read_pixel(self, img, use_memmap):
        img.read_pixel(100, 100, use_memmap)

    @timed
    def read_band(self, img, use_memmap):
        img.read_band(100, use_memmap)

    @timed
    def read_bands(self, img, use_memmap):
        img.read_bands([20, 30, 150], use_memmap)

    @timed
    def read_subregion(self, img, use_memmap):
        img.read_subregion((40, 150), (30, 200), None, use_memmap)

    @timed
    def read_subimage(self, img, use_memmap):
        img.read_subimage(range(200, 400, 3), range(300, 500, 2), None, use_memmap)

    @timed
    def read_datum(self, img, use_memmap):
        img.read_datum(30, 300, 150, use_memmap)

    def run(self):
        import os
        if not os.path.isfile('bilfile.hdr'):
            print 'Creating interleave files...'
            create_files()
        images = ['%sfile.hdr' % s for s in ['bil', 'bip', 'bsq']]
        names = ['band', 'bands', 'pixel', 'subregion', 'subimage', 'datum']
        tests = [self.read_band, self.read_bands, self.read_pixel,
                 self.read_subregion, self.read_subimage, self.read_datum]
        print 'Speedups using memmap in read methods:\n'
        print '{:15} {:^10} {:^10} {:^10}'.format('method', 'BIL', 'BIP', 'BSQ')
        print '-' * 48
        for (n, t) in zip(names, tests):
            speedups = [t(img, False) / t(img, True) for img in images]
#            speedups = [1. / (t(img, True) / t(img, False)) for img in images]
            print '{0:15} {1[0]:^10.2f} {1[1]:^10.2f} {1[2]:^10.2f}'.format('read_' + n, speedups)

if __name__ == '__main__':
    timer = FileTimer()
    timer.run()