Popular recipes tagged "meta:loc=17"

Get the inversion number of a permutation (Python)

2016-02-21T06:00:46-08:00

Python recipe 579051 by Samuel James Erickson (combinatorics, discrete, inversion, math, permutations). Revision 2.

This function takes a permutation in the form of a list and returns the number of inversions in the permutation.

Image Converter (Python)

2015-01-18T19:14:38-08:00

Python recipe 579007 by FB36 (conversion, conversions, convert, converter, image, images, pil).

Converts an image from one format to another using PIL.

eMail address list validation (JavaScript)

2014-02-05T22:21:03-08:00

JavaScript recipe 578823 by SoftMoon WebWare . Revision 0.

A bit of Regular Expressions to test whether a given string conforms to being an eMail address or comma-separated list of them.

eMail address list validation (JavaScript)

2014-02-05T22:20:41-08:00

JavaScript recipe 578822 by SoftMoon WebWare . Revision 0.

A bit of Regular Expressions to test whether a given string conforms to being an eMail address or comma-separated list of them.

Holiday Tree (Python)

2013-12-02T09:50:55-08:00

Python recipe 578778 by Bill Pickett (exercise). Revision 2.

Just a little holiday tree, would make a good exercise for beginning Python programmers.

heap class (Python)

2015-09-17T12:41:15-07:00

Python recipe 578694 by yota (heap). Revision 2.

heapq is a nice python module, but the interface is not so clean. I found a one-liner on this blog, it's as short as possible, but not really pythonic either :) Here is my contribution to a most readable heap class.

find + grep (Bash)

2013-09-17T08:48:07-07:00

Bash recipe 578661 by yota (find, grep, zsh). Revision 2.

look for a text pattern in files defined by a pattern. First argument is passed to the find command, second one to the grep

./find_n_grep.sh '*.py' 'dict'

more over, it sort by date.

Mounted devices2 (Batch)

2013-08-19T08:46:54-07:00

Batch recipe 578645 by greg zakharov .

Another way to check mounted drives (this method has a bug with cdrom).

A simple KD Tree example with custom Euclidean distance ball query. (Python)

2013-01-24T10:28:24-08:00

Python recipe 578434 by alexander baker (algorithms, python).

In computer science, a k-d tree (short for k-dimensional tree) is a space-partitioning data structure for organizing points in a k-dimensional space. k-d trees are a useful data structure for several applications, such as searches involving a multidimensional search key (e.g. range searches and nearest neighbor searches). k-d trees are a special case of binary space partitioning trees.

http://en.wikipedia.org/wiki/K-d_tree

Reversing string (JavaScript)

2013-02-18T09:27:33-08:00

JavaScript recipe 578464 by greg zakharov (reverse, string).

Two ways reverse string.

Greatest Common Divisor using Recursion in Python (Python)

2013-01-16T16:44:46-08:00

Python recipe 578421 by Captain DeadBones (gcd, math, python).

I wrote this little piece of code as part of my ongoing python-math projects. For more information please checkout The Living Pearl.

Detect screen resolution without wmi (part 2) (Batch)

2012-12-12T12:40:24-08:00

Batch recipe 578377 by greg zakharov (resolution, screen).

In previous time I wrote how to do it with mshta.exe. Good, now I want to show you how to do it with COM-object htmlfile. It looks like similar way with mshta.exe:

String to Binary (Python)

2014-07-30T07:20:22-07:00

Python recipe 578291 by p@ntut$ (binary, string, to). Revision 2.

String to binary snippet, python3+

Simple directory tree view generator (Python)

2012-03-09T09:02:21-08:00

Python recipe 578065 by ajaymenon.k (directory, tree).

An extremely simple tree-view generator for a directory

(Ab)Using Modules as Namespaces (Python)

2012-05-10T04:14:06-07:00

Python recipe 578122 by Wolfgang Scherer (module, namespaces, vars).

I have previously built a shar-like Python utility, which reads (marked) imported modules, gzips and base64 encodes them, then generates a python script, which is fully standalone.

The included module source is placed into sys.modules at runtime, making imports possible without actually having the module files installed. A very nice thing for administrative scripts that have to work in unconfigured environments.

At that time I discovered a lot of information about how modules in Python work.

Reading the very interesting recipe at http://code.activestate.com/recipes/577887-a-simple-namespace-class/ made me realize, that modules are actually very useful as generic namespaces too.

Fast Sorting of n dimensional array by first dimension (Python)

2012-03-14T15:14:11-07:00

Python recipe 578074 by Garrett (argsort, lists, numpy, python, sorting).

I have looked far and wide for code for fast sorting of n dimensional arrays by the first element, for example if I had the array:
ray = [[1,2,3,7,5][10,11,12,13,14]]

I would want it to come out as ray = [[1,2,3,5,7][10,11,12,14,13]]

There are several ways to do this. One is zipped = zip(ray) zipped.sort() ray = zip(zipped)

but this is extremely slow. Numpy has a much faster way to do it, but it wasn't immediately apparent.

if the above were a numpy array you could simply do the following: indexes = numpy.argsort(ray[0]) for n in xrange(len(ray)) ray[n] = ray[n][indexes]

I did a time test of the two methods below.

format_iter: easy formatting of arbitrary iterables (Python)

2011-08-16T11:44:59-07:00

Python recipe 577845 by Nick Coghlan (formatting, strings).

The format_iter recipe defines a simple wrapper around str.join and str.format that makes it easy to format an arbitrary iterable with a specified format string and item separator.

Minimal console python (Python)

2011-03-23T20:17:53-07:00

Python recipe 577622 by jrovegno .

Interpretador de linea de comandos python, sólo para uso didáctico, no debe utilizarse en producción. Referencia http://www.programando.org/blog/2011/03/repl/

Pascal's triangle (Python)

2011-01-14T00:29:05-08:00

Python recipe 577542 by Michael Puckett (pascal, triangle). Revision 5.

Pascal's triangle was a challenge on a forum I frequent today and this is what I came up with:

External Counter (Python)

2010-11-07T03:25:34-08:00

Python recipe 577456 by Stephen Chappell (counter).

Written as a tribute to recipe 440636, this newest version is considerably reworked.