Python Short URL Generator (Python)

2011-09-19T14:06:36-07:00

Python recipe 576918 by Michael Fogleman (deterministic, generator, short, tiny, unique, url). Revision 3.

Python implementation for generating Tiny URL- and bit.ly-like URLs.

Long period random number generator (Python)

2010-12-02T05:19:25-08:00

Python recipe 576707 by Raymond Hettinger (generator, number, random). Revision 13.

Implements a complementary-multiply-with-carry psuedo-random-number-generator. Period is 3636507990 * 2 ** 43487 (approximately 10 ** 13101).

grep in Python (Python)

2014-03-05T19:47:50-08:00

Python recipe 578845 by Andy Dustman (generator, grep, search).

The grep() function is inspired by UNIX grep, but is not limited to string patterns and files or streams.

Python Short URL Generator (Python)

2014-11-09T11:19:07-08:00

Python recipe 578961 by Des Wagner (deterministic, generator, short, tiny, unique, url).

Python implementation for generating Tiny URL- and bit.ly-like URLs.

Run asynchronous tasks using coroutines (Python)

2010-08-06T16:16:20-07:00

Python recipe 577129 by Arnau Sanchez (coroutine, event, generator, gobject, gtk, gui, network, nonblocking, pygtk). Revision 20.

This recipe shows a simple, transparent (and hopefully pythonic) way of running asynchronous tasks when writing a event-driven application (i.e. GUI). The aim is to allow a programmer to write time-consuming functions (usually IO-bound, but not only) with sequential-looking code, instead of scattering the logic over a bunch of callbacks. We will take advantage of the coroutines introduced in Python 2.5 (see http://www.python.org/dev/peps/pep-0342).

The goal: wouldn't it be great if we could write something like this?

def myjob(entry, arg1, arg2, arg3):
    result1 = function_that_takes_eons_to_complete(arg1, arg2)    
    result2 = another_function_that_downloads_a_big_really_big_file(result1, arg3)
    entry.set_text("The result is: %d" % result2)

def on_start_button___clicked(button, entry):
    myjob(entry, 1, 2, 3)

...    
gtk.main()

Indeed, but we can't! The GUI will hang until the job is done and the user will be rightfully angry. Coroutines to the rescue: the absolute minimal change we can make to this code is transforming myjob into a coroutine and yield every time we do blocking stuff:

def myjob(entry, arg1, arg2, arg3):
    result1 = yield some_task(arg1, arg2)    
    result2 = yield some_other_task(result1, arg3)
    entry.set_text("The result is: %d" % result2)

def on_start__clicked(button, entry):
    start_job(myjob(entry, 1, 2, 3))

some_task and some_other_task are here the asynchronous implementation of the sequential tasks used in the first fragment, and start_job the wrapper around the coroutine. Note that we still have to implement non-blocking versions of the tasks, but they are usually pretty generic (wait some time, download a file, ...) and can be re-used. If you happen to have a CPU-bound function or even a IO-bound code you cannot split (urllib2 anyone?), you can always use a generic threaded task (granted, the whole point of using co-routines should be avoiding threads, but there is no alternative here).

At the end, all the plumbing we need to make it work is just 1 function: start_job (wrapper around the job to manage the flow of the coroutine). The rest of the code -two asynchronous tasks (sleep_task, threaded_task) and a demo app- are shown solely as an example.

Generate a salt (PHP)

2012-07-10T19:52:17-07:00

PHP recipe 576894 by Xavier L. (crypt, generation, generator, hash, pass, password, salt, secure, security, string). Revision 6.

This function will generate a salt for use with passwords ranging using characters in range a to z, A to Z, 0 to 9 and !@#$%&?. The characters are sorted in a random value and can appear more than one time in the string. This way, this function is more powerful than the *shuffle() function. This means that the salt could also be longer than the character list.

Basic class code generator (Python)

2010-03-22T10:58:19-07:00

Python recipe 577130 by Mateyuzo (generator, prototyping, template). Revision 5.

This little script takes a yaml file as a class definition and generates code stubs and unit tests.

Simple White Noise Generator Using Standard Python In Linux. (Python)

2011-03-10T18:03:55-08:00

Python recipe 577604 by Barry Walker (audio, demo, generator, linux, noise, program, signal, sound, source).

Simple White Noise Generator Using Standard Python In Linux - noise.py

This code is a stand alone program to generate a signal, at the earphone sockets, of white noise.

It needs /dev/dsp to work; if you haven't got it then install oss-compat from your distro's repository. (NOTE:- /dev/audio could also be used but I decided to use /dev/dsp to show that this was within easy reach of standard Python too.)

Ensure the audio system is NOT in use for this to work and all the levels are set up for your normal requirements. In my case root level WAS NOT required but that does not mean that root level IS NOT required - so be aware.

All that is required to make this a piece of audio test equipment is a cable plugged into to the earphone socket. The output level is fully controllable inside the code and the noise is generated in about 10 second bursts

Assuming it is copied into the module(s) drawer just type:-

>>> import noise[RETURN/ENTER]

And away you go...

This is Public Domain and you may do with it as you like.

Read the program for more information. (There will be more to come in the future... :)

Enjoy finding simple solutions to often very difficult problems... ;o)

73...

Bazza, G0LCU...

Team AMIGA...

Retry loop (Python)

2013-05-24T05:19:50-07:00

Python recipe 578163 by Oren Tirosh (exception, generator, loop, retry, timeout). Revision 4.

Encapsulates the logic of a retry loop using a generator function.

Simple 1KHz Audio Function Generator Using Standard Python In Linux... (Python)

2011-03-01T19:37:16-08:00

Python recipe 577592 by Barry Walker (audio, demo, function, generator, linux, program, signal, sound, source).

Simple 1KHz Audio Function Generator Using Standard Python In Linux - afg.py

This code is a stand alone program to generate a signal, at the earphone sockets, of 1KHz. It is a basic audio signal generator and can be used as a starter test signal source for amateur electronics enthusiasts testgear suite(s).

It needs /dev/audio to work; if you haven't got it then install oss-compat from your distro's repository.

Ensure the audio system is NOT in use for this to work.

Sine, Square, Triangle, Sawtooth+, Sawtooth-, Pulse+ and Pulse- signals are generated in 10 second bursts. The waveforms generated are unfiltered and therefore not "pure", but hey, an audio function generator signal source, for free, without external hardware, AND, using standard Python, what more do you want... :) An oscilloscope will show the waveforms generated at the earphone socket.

Noise is not included but that is SO easy that I left it out FTTB. (This will be a future upload. ;o)

All that is required to make this a piece of audio test equipment is a cable plugged into to the earphone socket.

Assuming it is copied into the module(s) drawer just type:-

>>> import afg[RETURN/ENTER]

And away you go...

This is Public Domain and you may do with it as you like.

Read the program for more information. (There will be more to come in the future... :)

Planet Terrain Heightmap Generator (Python)

2010-03-10T16:35:37-08:00

Python recipe 576929 by Shea Kauffman (creation, generation, generator, heightmap, landscape, map, pil, planet, planted, pygame, terrain, world). Revision 9.

The process is simply: 1. Take a plane 2. Cut out a shape 3. Make it a little taller 4. Repeat

Similar to the spherical landscape algorithm by Hugo Elias.
I found a combination of Ovals and Triangles to produce the best results.

Asynchronous subprocess using asyncore (Python)

2013-01-21T19:51:00-08:00

Python recipe 576957 by Glenn Eychaner (async, asynchronous, asyncore, coroutine, decorator, generator, ipc, subprocess). Revision 21.

A coroutine-based wrapper for subprocess.Popen that uses asyncore to communicate with child processes asynchronously. This allows subprocesses to be called from within socket servers or clients without needing a complicated event loop to check both. Uses recipe 576965 to provide the asynchronous coroutine framework, recipe 576967 to provide asynchronous pipes, and recipe 577600 to provide multiple alarms.

sin, cos, tan for Decimal (Python)

2007-07-05T19:49:49-07:00

Python recipe 523018 by Alain Mellan (algorithms, generator). Revision 2.

Implementation of sine, cosine, tangent functions for Decimal arithmetic, using Taylor series expansion. It uses simple numerator and denominator generators.

The nice part is, the code is independent from the Decimal library. Feed it a float, it works just the same as if you feed it a Decimal (apart from the precision :-)

Random Password Generation (Python)

2014-08-10T15:50:40-07:00

Python recipe 578920 by Paul Wolf (generator, password, python, random, string, strong).

Generate a password (or other secure token) using a pattern language similar to regular expressions. We'll use the strgen module that enables a user to generate test data, unique ids, passwords, vouchers or other randomized data very quickly using a template language. The template language is superficially similar to regular expressions but instead of defining how to match or capture strings, it defines how to generate randomized strings.

Run async code inline, nonblocking (Python)

2009-11-11T12:55:01-08:00

Python recipe 576952 by Thomas Ahle (asynchronous, closure, decorator, generator, threads). Revision 7.

A decorator, that makes it easy to switch between the mainthread and background threads.

Password Generator (mkpasswd) (Python)

2013-07-31T23:23:02-07:00

Python recipe 578468 by James Mills (generator, mkpasswd, password, secure). Revision 3.

Since everyone is posting one of these, I thought I'd post mine. I wrote this many years ago and use it everywhere.

Password Generator (Python)

2011-10-14T13:35:21-07:00

Python recipe 577905 by Alexander Thomas Cruz (generator, password, randomization). Revision 4.

Generates a really strong and secure password. It uses multiple characters and symbols. Remember to score please! It really means a lot to me. Revision 4 includes an input so you can choose how many characters you want your password to have. It is also faster due to a suggestion by Garel Alex. Thanks!

Prime Number Generator (Python)

2009-02-03T15:47:06-08:00

Python recipe 576640 by dth (eratosthene, generator, number, of, prime, sieve). Revision 7.

Generate all prime numbers up to n.

Retry loop (Python)

2013-05-23T20:45:01-07:00

Python recipe 578527 by Ryan Nowakowski (exception, generator, loop, retry, timeout).

Encapsulates the logic of a retry loop using a generator function.

And yet another round-robin generator (Python)

2013-11-13T19:30:29-08:00

Python recipe 578768 by Jan Müller (generator, itertools, python, roundrobin).

I know that there is a nice recipe already that even made it into the Python documentation, but this one is more concise and at the same time simpler.

>>> list(roundrobin('ABC', 'D', 'EF'))
['A', 'D', 'E', 'B', 'F', 'C']

Most viewed recipes tagged "generator"

Python Short URL Generator (Python)

Long period random number generator (Python)

grep in Python (Python)

Python Short URL Generator (Python)

Run asynchronous tasks using coroutines (Python)

Generate a salt (PHP)

Basic class code generator (Python)

Simple White Noise Generator Using Standard Python In Linux. (Python)

Retry loop (Python)

Simple 1KHz Audio Function Generator Using Standard Python In Linux... (Python)

Simple 1KHz Audio Function Generator Using Standard Python In Linux - afg.py

Planet Terrain Heightmap Generator (Python)

Asynchronous subprocess using asyncore (Python)

sin, cos, tan for Decimal (Python)

Random Password Generation (Python)

Run async code inline, nonblocking (Python)

Password Generator (mkpasswd) (Python)

Password Generator (Python)

Prime Number Generator (Python)

Retry loop (Python)

And yet another round-robin generator (Python)