We give a simple class for marking the time at different points in a code block and then printing out the time gaps between adjacent marked points. This is useful for identifying slow spots in code.

The TimeMarker class

In the past, whenever I needed to speed up a block of python code, the first thing I would do was import the time package, then manually insert a set of lines of the form t1 = time.time(), t2 = time.time(), etc. Then at the end, print t2 - t1, t3 -t2, ..., etc. This works reasonably well, but I found it annoying and time consuming to have to save each time point to a different variable name. In particular, this prevented quick copy and paste of the time marker line. I finally thought to fix it this evening: Behold the TimeMarker class, which solves this problem for me:

import time

class TimeMarker():

def __init__(self):  
    self.markers = []

def mark(self):  
    self.markers.append(time.time())

def print_markers(self):  
    for pair in zip(self.markers, self.markers[1:]):  
    print pair[1] - pair[0]  

Here is a simple code example:

tm = TimeMarker()

tm.mark()  
sum(range(10 ** 2))  
tm.mark()  
sum(range(10 ** 6))  
tm.mark()

tm.print_markers()  
# (output...)  
# 7.9870223999e-05  
# 0.0279731750488  

The key here is that I can quickly paste the tm.mark() repeatedly throughout my code and quickly check where the slow part sits.

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Jonathan Landy Avatar Jonathan Landy Jonathan grew up in the midwest and then went to school at Caltech and UCLA. Following this, he did two postdocs, one at UCSB and one at UC Berkeley.  His academic research focused primarily on applications of statistical mechanics, but his professional passion has always been in the mastering, development, and practical application of slick math methods/tools. He worked as a data-scientist at Square for four years and is now working on a quantitative investing startup.
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