Python OpenCV sample subset images

sample subset images from many images

import sys,osdef fileCountIn(dir):    return sum([len(files) for root,dirs,files in os.walk(dir)])print "sample images:"path = "/home/qz/Desktop/CalibGoProHero4/intrinsic/src3/"newpath = "/home/qz/Desktop/CalibGoProHero4/intrinsic/src/"fileCount = fileCountIn(path)print fileCountsample_ratio = 0.025sample_digits = int(1/sample_ratio)print sample_digitsindex = 1for filename in os.listdir(path):    index = index +1    if(index%sample_digits==0):        print filename        img = cv2.imread(path + filename)        img = cv2.transpose(img)        img = cv2.flip(img,1 )        new_name = newpath + filename        cv2.imwrite(new_name, img)