Improvements of description. Thanks to sigmavirus24

This commit is contained in:
tommy3001
2014-02-23 23:32:13 +01:00
parent 33b428b8a5
commit b8f9923416
+23 -17
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@@ -69,12 +69,14 @@ Cython
------
With `Cython <http://cython.org/>`_ you are able to write C and C++ modules for Python. It implements a superset of the Python language.
With Cython you are also able to call C-functions and realize strong typing of variables and functions like float
(floating point numbers) or int (integer) definition of variables. Here is an example of strong typing with Cython:
You are also able to call C-functions and realize declaration of variables and functions like in C. Here is an example:
.. code-block:: python
def primes(int kmax):
"""Calculation of prime numbers with additional
Cython keywords"""
cdef int n, k, i
cdef int p[1000]
result = []
@@ -94,11 +96,14 @@ With Cython you are also able to call C-functions and realize strong typing of v
return result
This implementation of an algorithm to find prime numbers has some additional commands instead of the next one, which is implemented in pure Python:
This implementation of an algorithm to find prime numbers has some additional keywords instead of the next one, which is implemented in pure Python:
.. code-block:: python
def primes( kmax):
def primes(kmax):
"""Calculation of prime numbers in standard Python syntax"""
p= range(1000)
result = []
if kmax > 1000:
@@ -120,28 +125,30 @@ This implementation of an algorithm to find prime numbers has some additional co
The only difference between the both algorithm is this part:
Strong typing with Cython:
.. code-block:: python
#primes function with additional Cython code:
def primes(int kmax):
"""Calculation of prime numbers with additional
Cython keywords"""
cdef int n, k, i
cdef int p[1000]
result = []
Normal variable definition in Python:
.. code-block:: python
#primes in standard Python syntax:
def primes( kmax):
def primes(kmax):
"""Calculation of prime numbers in standard Python syntax"""
p= range(1000)
result = []
What is the difference? In the upper Cython version you can see the definitions of the variable types like in standard C.
For example `cdef int n,k,i` in line 3. This additional type definition (e.g. integer) allows the Cython compiler to generate
more efficient C code from this Cython code. While standard Python code is saved in `*.py` files, the Cython code is saved in `*.pyx` files.
What is the difference? In the upper Cython version you can see the declaration of the variable types and the integer array
in a similar way like in standard C. For example `cdef int n,k,i` in line 3. This additional type declaration (e.g. integer)
allows the Cython compiler to generate more efficient C code from the second code. While standard Python code is saved in `*.py` files,
Cython code is saved in `*.pyx` files.
And what is with the speed? So lets try it!
@@ -169,7 +176,7 @@ And what is with the speed? So lets try it!
print "Python time: %s" %(t2-t1)
Where is the magic? Here it is:
These both lines need a remark:
.. code-block:: python
@@ -177,11 +184,10 @@ Where is the magic? Here it is:
pyximport.install()
With the module `pyximport` you are able to import Cython `*.pyx` files, in this case `primesCy.pyx`, with the Cython
version of the primes function.
The `pyximport` module allows you to import `pyx` files (e.g., `primesCy.pyx`) with the Cython-compiled version of the `primes` function.
The `pyximport.install()` command allows the Python interpreter to start the Cython compiler directly to generate C-code,
which is automatically compiled to a `*.so` C-library. ... and Cython is able to import this library for you in your Python-code.
Very easy and very efficient. With the `time.time()` function you are able to compare the time between these 2 different calls to find 500 prime numbers.
which is automatically compiled to a `*.so` C-library. Cython is able to import this library for you in your Python-code.
Very easy and very efficient. With the `time.time()` function you are able to compare the time between this 2 different calls to find 500 prime numbers.
On a standard notebook (dualcore AMD E-450 1,6 GHz) the measured values are: