What is the Python equivalent of Matlab's tic and toc functions?

What is the Python equivalent of Matlab's tic and toc functions?

12 Answers

Apart from timeit which ThiefMaster mentioned, a simple way to do it is just (after importing time):

t = time.time() # do stuff elapsed = time.time() - t 

I have a helper class I like to use:

class Timer(object): def __init__(self, name=None): self.name = name def __enter__(self): self.tstart = time.time() def __exit__(self, type, value, traceback): if self.name: print('[%s]' % self.name,) print('Elapsed: %s' % (time.time() - self.tstart)) 

It can be used as a context manager:

with Timer('foo_stuff'): # do some foo # do some stuff 

Sometimes I find this technique more convenient than timeit - it all depends on what you want to measure.

I had the same question when I migrated to python from Matlab. With the help of this thread I was able to construct an exact analog of the Matlab tic() and toc() functions. Simply insert the following code at the top of your script.

import time def TicTocGenerator(): # Generator that returns time differences ti = 0 # initial time tf = time.time() # final time while True: ti = tf tf = time.time() yield tf-ti # returns the time difference TicToc = TicTocGenerator() # create an instance of the TicTocGen generator # This will be the main function through which we define both tic() and toc() def toc(tempBool=True): # Prints the time difference yielded by generator instance TicToc tempTimeInterval = next(TicToc) if tempBool: print( "Elapsed time: %f seconds.\n" %tempTimeInterval ) def tic(): # Records a time in TicToc, marks the beginning of a time interval toc(False) 

That's it! Now we are ready to fully use tic() and toc() just as in Matlab. For example

tic() time.sleep(5) toc() # returns "Elapsed time: 5.00 seconds." 

Actually, this is more versatile than the built-in Matlab functions. Here, you could create another instance of the TicTocGenerator to keep track of multiple operations, or just to time things differently. For instance, while timing a script, we can now time each piece of the script seperately, as well as the entire script. (I will provide a concrete example)

TicToc2 = TicTocGenerator() # create another instance of the TicTocGen generator def toc2(tempBool=True): # Prints the time difference yielded by generator instance TicToc2 tempTimeInterval = next(TicToc2) if tempBool: print( "Elapsed time 2: %f seconds.\n" %tempTimeInterval ) def tic2(): # Records a time in TicToc2, marks the beginning of a time interval toc2(False) 

Now you should be able to time two separate things: In the following example, we time the total script and parts of a script separately.

tic() time.sleep(5) tic2() time.sleep(3) toc2() # returns "Elapsed time 2: 5.00 seconds." toc() # returns "Elapsed time: 8.00 seconds." 

Actually, you do not even need to use tic() each time. If you have a series of commands that you want to time, then you can write

tic() time.sleep(1) toc() # returns "Elapsed time: 1.00 seconds." time.sleep(2) toc() # returns "Elapsed time: 2.00 seconds." time.sleep(3) toc() # returns "Elapsed time: 3.00 seconds." # and so on... 

I hope that this is helpful.

The absolute best analog of tic and toc would be to simply define them in python.

def tic(): #Homemade version of matlab tic and toc functions import time global startTime_for_tictoc startTime_for_tictoc = time.time() def toc(): import time if 'startTime_for_tictoc' in globals(): print "Elapsed time is " + str(time.time() - startTime_for_tictoc) + " seconds." else: print "Toc: start time not set" 

Then you can use them as:

tic() # do stuff toc() 

Usually, IPython's %time, %timeit, %prun and %lprun (if one has line_profiler installed) satisfy my profiling needs quite well. However, a use case for tic-toc-like functionality arose when I tried to profile calculations that were interactively driven, i.e., by the user's mouse motion in a GUI. I felt like spamming tics and tocs in the sources while testing interactively would be the fastest way to reveal the bottlenecks. I went with Eli Bendersky's Timer class, but wasn't fully happy, since it required me to change the indentation of my code, which can be inconvenient in some editors and confuses the version control system. Moreover, there may be the need to measure the time between points in different functions, which wouldn't work with the with statement. After trying lots of Python cleverness, here is the simple solution that I found worked best:

from time import time _tstart_stack = [] def tic(): _tstart_stack.append(time()) def toc(fmt="Elapsed: %s s"): print fmt % (time() - _tstart_stack.pop()) 

Since this works by pushing the starting times on a stack, it will work correctly for multiple levels of tics and tocs. It also allows one to change the format string of the toc statement to display additional information, which I liked about Eli's Timer class.

For some reason I got concerned with the overhead of a pure Python implementation, so I tested a C extension module as well:

#include <Python.h> #include <mach/mach_time.h> #define MAXDEPTH 100 uint64_t start[MAXDEPTH]; int lvl=0; static PyObject* tic(PyObject *self, PyObject *args) { start[lvl++] = mach_absolute_time(); Py_RETURN_NONE; } static PyObject* toc(PyObject *self, PyObject *args) { return PyFloat_FromDouble( (double)(mach_absolute_time() - start[--lvl]) / 1000000000L); } static PyObject* res(PyObject *self, PyObject *args) { return tic(NULL, NULL), toc(NULL, NULL); } static PyMethodDef methods[] = { {"tic", tic, METH_NOARGS, "Start timer"}, {"toc", toc, METH_NOARGS, "Stop timer"}, {"res", res, METH_NOARGS, "Test timer resolution"}, {NULL, NULL, 0, NULL} }; PyMODINIT_FUNC inittictoc(void) { Py_InitModule("tictoc", methods); } 

This is for MacOSX, and I have omitted code to check if lvl is out of bounds for brevity. While tictoc.res() yields a resolution of about 50 nanoseconds on my system, I found that the jitter of measuring any Python statement is easily in the microsecond range (and much more when used from IPython). At this point, the overhead of the Python implementation becomes negligible, so that it can be used with the same confidence as the C implementation.

I found that the usefulness of the tic-toc-approach is practically limited to code blocks that take more than 10 microseconds to execute. Below that, averaging strategies like in timeit are required to get a faithful measurement.

You can use tic and toc from ttictoc. Install it with

pip install ttictoc 

And just import them in your script as follow

from ttictoc import tic,toc tic() # Some code print(toc()) 

I have just created a module [tictoc.py] for achieving nested tic tocs, which is what Matlab does.

from time import time tics = [] def tic(): tics.append(time()) def toc(): if len(tics)==0: return None else: return time()-tics.pop() 

And it works this way:

from tictoc import tic, toc # This keeps track of the whole process tic() # Timing a small portion of code (maybe a loop) tic() # -- Nested code here -- # End toc() # This returns the elapse time (in seconds) since the last invocation of tic() toc() # This does the same for the first tic() 

I hope it helps.

Have a look at the timeit module. It's not really equivalent but if the code you want to time is inside a function you can easily use it.

pip install easy-tictoc 

In the code:

from tictoc import tic, toc tic() #Some code toc() 

^{Disclaimer: I'm the author of this library.}

This can also be done using a wrapper. Very general way of keeping time.

The wrapper in this example code wraps any function and prints the amount of time needed to execute the function:

def timethis(f): import time def wrapped(*args, **kwargs): start = time.time() r = f(*args, **kwargs) print "Executing {0} took {1} seconds".format(f.func_name, time.time()-start) return r return wrapped @timethis def thistakestime(): for x in range(10000000): pass thistakestime() 

I changed @Eli Bendersky's answer a little bit to use the ctor __init__() and dtor __del__() to do the timing, so that it can be used more conveniently without indenting the original code:

class Timer(object): def __init__(self, name=None): self.name = name self.tstart = time.time() def __del__(self): if self.name: print '%s elapsed: %.2fs' % (self.name, time.time() - self.tstart) else: print 'Elapsed: %.2fs' % (time.time() - self.tstart) 

To use, simple put Timer("blahblah") at the beginning of some local scope. Elapsed time will be printed at the end of the scope:

for i in xrange(5): timer = Timer("eigh()") x = numpy.random.random((4000,4000)); x = (x+x.T)/2 numpy.linalg.eigh(x) print i+1 timer = None 

It prints out:

1 eigh() elapsed: 10.13s 2 eigh() elapsed: 9.74s 3 eigh() elapsed: 10.70s 4 eigh() elapsed: 10.25s 5 eigh() elapsed: 11.28s 

Building on Stefan and antonimmo's answers, I ended up putting

def Tictoc(): start_stack = [] start_named = {} def tic(name=None): if name is None: start_stack.append(time()) else: start_named[name] = time() def toc(name=None): if name is None: start = start_stack.pop() else: start = start_named.pop(name) elapsed = time() - start return elapsed return tic, toc 

in a utils.py module, and I use it with a

from utils import Tictoc tic, toc = Tictoc() 

This way

• you can simply use tic(), toc() and nest them like in Matlab
• alternatively, you can name them: tic(1), toc(1) or tic('very-important-block'), toc('very-important-block') and timers with different names won't interfere
• importing them this way prevents interference between modules using it.

(here toc does not print the elapsed time, but returns it.)

Updating Eli's answer to Python 3:

class Timer(object): def __init__(self, name=None, filename=None): self.name = name self.filename = filename def __enter__(self): self.tstart = time.time() def __exit__(self, type, value, traceback): message = 'Elapsed: %.2f seconds' % (time.time() - self.tstart) if self.name: message = '[%s] ' % self.name + message print(message) if self.filename: with open(self.filename,'a') as file: print(str(datetime.datetime.now())+": ",message,file=file) 

Just like Eli's, it can be used as a context manager:

import time with Timer('Count'): for i in range(0,10_000_000): pass 

Output:

[Count] Elapsed: 0.27 seconds 

I have also updated it to print the units of time reported (seconds) and trim the number of digits as suggested by Can, and with the option of also appending to a log file. You must import datetime to use the logging feature:

import time import datetime with Timer('Count', 'log.txt'): for i in range(0,10_000_000): pass