How to measure time taken between lines of code in python?

So in Java, we can do How to measure time taken by a function to execute

But how is it done in python? To measure the time start and end time between lines of codes? Something that does this:

import some_time_library

starttime = some_time_library.some_module()
code_tobe_measured() 
endtime = some_time_library.some_module()

time_taken = endtime - starttime

Solution 1:

If you want to measure CPU time, can use time.process_time() for Python 3.3 and above:

import time
start = time.process_time()
# your code here    
print(time.process_time() - start)

First call turns the timer on, and second call tells you how many seconds have elapsed.

There is also a function time.clock(), but it is deprecated since Python 3.3 and will be removed in Python 3.8.

There are better profiling tools like timeit and profile, however time.process_time() will measure the CPU time and this is what you're are asking about.

If you want to measure wall clock time instead, use time.time().

Solution 2:

You can also use time library:

import time

start = time.time()

# your code

# end

print(f'Time: {time.time() - start}')

Solution 3:

With a help of a small convenience class, you can measure time spent in indented lines like this:

with CodeTimer():
   line_to_measure()
   another_line()
   # etc...

Which will show the following after the indented line(s) finishes executing:

Code block took: x.xxx ms

UPDATE: You can now get the class with pip install linetimer and then from linetimer import CodeTimer. See this GitHub project.

The code for above class:

import timeit

class CodeTimer:
    def __init__(self, name=None):
        self.name = " '"  + name + "'" if name else ''

    def __enter__(self):
        self.start = timeit.default_timer()

    def __exit__(self, exc_type, exc_value, traceback):
        self.took = (timeit.default_timer() - self.start) * 1000.0
        print('Code block' + self.name + ' took: ' + str(self.took) + ' ms')

You could then name the code blocks you want to measure:

with CodeTimer('loop 1'):
   for i in range(100000):
      pass

with CodeTimer('loop 2'):
   for i in range(100000):
      pass

Code block 'loop 1' took: 4.991 ms
Code block 'loop 2' took: 3.666 ms

And nest them:

with CodeTimer('Outer'):
   for i in range(100000):
      pass

   with CodeTimer('Inner'):
      for i in range(100000):
         pass

   for i in range(100000):
      pass

Code block 'Inner' took: 2.382 ms
Code block 'Outer' took: 10.466 ms

Regarding timeit.default_timer(), it uses the best timer based on OS and Python version, see this answer.