timer.py

class Timer(object):

    def __init__(self):
        self.start = None
        self.l = []

    def mark(self, name=''):
        from time import time
        if name:
            print name + ' marked.'

        if not self.start:
            self.start = time()
        else:
            t = time() - self.start
            diff = 0
            if self.l:
                diff = t - self.l[len(self.l) - 1][1]

            self.l.append((name , t, diff))

    def clear(self):
        self.l = []

    def __repr__(self):
        r = ""
        for i, x in enumerate(self.l):
            if x[0]:
                r += "%d mark `%s`, %.2f seconds, %.2fs consumed\n" % (i, x[0], x[1], x[2])
            else:
                r += "%d mark, %.2f seconds, %.2fs consumed\n\n" % (i, x[1], x[2])

        if self.l:
            avg = sum([x[2] for x in self.l]) / float(len(self.l))
            r += 'run %d in %.2fs, average: %.2fs\n' % (len(self.l),
                                                       self.l[len(self.l) - 1][1],
                                                       avg)
        return r

t = Timer()
t.mark()
#do some process
t.mark(name='process1')
#do another process
t.mark(name='process2')
print t
"""
 0 mark `process1`, 2.24 seconds
 1 mark `process2`, 3.34 seconds
"""