This is one of the 100 recipes of the IPython Cookbook, the definitive guide to high-performance scientific computing and data science in Python.

4.3. Profiling your code line by line with line_profiler

Standard imports.

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import numpy as np

After installing line_profiler, we can export the IPython extension.

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%load_ext line_profiler

For %lprun to work, we need to encapsulate the code in a function, and to save it in a Python script..

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%%writefile simulation.py
import numpy as np

def step(*shape):
    # Create a random n-vector with +1 or -1 values.
    return 2 * (np.random.random_sample(shape) < .5) - 1

def simulate(iterations, n=10000):
    s = step(iterations, n)
    x = np.cumsum(s, axis=0)
    bins = np.arange(-30, 30, 1)
    y = np.vstack([np.histogram(x[i,:], bins)[0] for i in range(iterations)])
    return y

Now, we need to execute this script to load the function in the interactive namespace.

In [ ]:
import simulation

Let's execute the function under the control of the line profiler.

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%lprun -T lprof0 -f simulation.simulate simulation.simulate(50)
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print(open('lprof0', 'r').read())

Let's run the simulation with 10 times more iterations.

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%lprun -T lprof1 -f simulation.simulate simulation.simulate(iterations=500)
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print(open('lprof1', 'r').read())

You'll find all the explanations, figures, references, and much more in the book (to be released later this summer).

IPython Cookbook, by Cyrille Rossant, Packt Publishing, 2014 (500 pages).