Add sample code

Author: gjbex

source-code/README.md

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+# Source code
+
+This is source code that is either used in the presentation, or was developed
+to create it.  There is some material not covered in the presentation as well.
+
+## Requirements
+
+* Python version: at least 3.6
+* Packages (names listed taht can be used with `pip` or `conda` to install):
+  * cython
+  * dask
+  * numpy
+  * numexpr
+  * scipy
+  * matplotlib
+  * mpi4py
+  * pytables
+  * jupyter
+  * ipywidgets
+
+
+## What is it?
+
+1. `cython`: illustrations of how to use Cython to speed up Python.
+1. `dask`: examples of how to use dask for distributed computing.
+1. `interfaciing-c-c++-fortran`: illustrations of ctypes, SWIG and
+   f2py to interface with C, C++ and Fortran code.
+1. `ising`: example of speeding up a Python simulation by wrapping
+   C++ code using SWIG.
+1. `mpi4py`: illustrations of distributed programming using MPI.
+1. `multiprocessing`: illustrations of multithreaded programming
+   using multiprocessing.
+1. `numba`: illustration of using the numba library.
+1. `profiling`: some illustrations and how-to on profiling a Python
+   application.
+1. `pyspark`: illustrations of using PySpark.

source-code/cython/.gitignore

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+build
+*.so

source-code/cython/Exceptions/Makefile

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+VERSION = cpython-34m
+AVERAGE_LIB = average.$(VERSION).so
+
+all: $(AVERAGE_LIB)
+
+$(AVERAGE_LIB): average.pyx
+	python setup.py build_ext --inplace
+
+clean:
+	python setup.py clean
+	rm -f average.c $(AVERAGE_LIB)

source-code/cython/Exceptions/README.md

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+# Exceptions
+Error handling in Cython code.
+
+## What is it?
+1. `average.pyx`: code to be compiled using Cython, implements two
+    functions to compute the average of an array slice, one with, the
+    other without error handling.
+1. `setup.py`: Python build script.
+1. `Makefile`: make file to build the extension.
+1. `compute_average.py`: script to load the compiled module and call the
+    implemented function with and without error handling.

source-code/cython/Exceptions/average.pyx

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+def average(data, m=0, n=None):
+    if n is None:
+        n = len(data)
+    return _average(memoryview(data), m, n)
+
+def average_no_except(data, m=0, n=None):
+    if n is None:
+        n = len(data)
+    return _average_no_except(memoryview(data), m, n)
+
+cdef double _average(data, int m=0, int n=-1) except? -1.0:
+    cdef int i
+    cdef double mean = 0.0
+    for i in range(m, n):
+        mean += data[i]
+    return mean/(n - m + 1)
+
+cdef double _average_no_except(data, int m=0, int n=-1):
+    cdef int i
+    cdef double mean = 0.0
+    for i in range(m, n):
+        mean += data[i]
+    return mean/(n - m + 1)

source-code/cython/Exceptions/compute_average.py

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+#!/usr/bin/env python
+
+from argparse import ArgumentParser
+import array
+import average
+
+
+size = 10
+
+arg_parser = ArgumentParser(description='test Cython errors')
+arg_parser.add_argument('--m', type=int, default=0, help='lower bound')
+arg_parser.add_argument('--n', type=int, default=size, help='upper bound')
+options = arg_parser.parse_args()
+data = array.array('d', list(range(size)))
+print('with except:')
+try:
+    print(average.average(data, options.m, options.n))
+except Exception as e:
+    print('caught exception {0}: {1}'.format(str(e.__class__), str(e)))
+print('without except:')
+try:
+    print(average.average_no_except(data, options.m, options.n))
+    print('no exception caught')
+except Exception as e:
+    print('caught exception {0}: {1}'.format(e.__class__, str(e)))

source-code/cython/Exceptions/setup.py

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+#!/usr/bin/env python
+
+from distutils.core import setup
+from Cython.Build import cythonize
+
+setup(
+    ext_modules=cythonize('average.pyx')
+)

source-code/cython/HelloWorld/Makefile

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+VERSION = cpython-34m
+HELLO_WORLD_LIB = hello_world.$(VERSION).so
+
+all: $(HELLO_WORLD_LIB)
+
+$(HELLO_WORLD_LIB): hello_world.pyx
+	python setup.py build_ext --inplace
+
+clean:
+	python setup.py clean
+	rm -f hello_world.c $(HELLO_WORLD_LIB)

source-code/cython/HelloWorld/README.md

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+# HelloWorld
+Most trivial example of Cython code.
+
+## What is it?
+1. `hello_world.pyx`: code to be compiled using Cython.
+1. `setup.py`: Python build script.
+1. `Makefile`: make file to build the extension.
+1. `say_hello.py`: script to load the compiled module.  Note that the code
+    is executed upon import since no guard is in place.

source-code/cython/HelloWorld/hello_world.pyx

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+print('hello world!')