Latest recipes tagged "unique"

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.

Multiple unique class instances - a tentative design pattern (Python)

2013-02-23T14:11:44-08:00

Python recipe 578471 by Moritz Beber (design_pattern, pattern, unique).

Coming from Bioinformatics and having to deal with multiple objects with unique properties, like genes, proteins, and many more, I felt the need for a class that would always yield a unique instance based on a chosen identifier. This is because I always wanted the same instances whose attributes were filled with information and track them in various storage classes, like dictionaries, lists, etc. The code for the class lives over on github. Recently, I've added a lot of parallel-processing code so I adapted the pickling behaviour for this class to also yield existing instances. What follows is an example of how to use it and some discussion questions.

Find a unique name based on prefix + digit in log2(n) + log2(n/2) (Python)

2011-10-31T20:30:54-07:00

Python recipe 577934 by Garel Alex (name, unique).

Find a unique name based on a prefix for a content in a container (eg. a file in a directory) adding a digit to the name

Does it in log2(n) + log2(n/2) were n is the number of duplicates

This would be used eg. in a CMS giving identifiers based on content title, or when shortening file names on a file system, etc.

lazy ordered unique elements from an iterator (Python)

2011-06-23T16:36:38-07:00

Python recipe 577768 by Andrew Dalke (iterator, itertools, unique). Revision 2.

This implements a "unique" filter. Its input is an iterator of hashable items. It returns an iterator containing only the unique items of the input, in input order. That is, list(unique("cabbage")) produces ["c", "a", "b", "g"]. The implementation is lazy. The function supports the "key" parameter, which provides an alternate form of comparison.

(Note: a better version of this is available from the itertools documentation as unique_everseen )

YouTube-like primary key generation (PHP)

2011-02-24T21:43:55-08:00

PHP recipe 577571 by Slava Yanson (activerecord, database, php, unique). Revision 4.

If you have more then 1 primary database servers - you have probably experienced the pain of primary key overlapping... Here is a super simple solution that will generate a hash of random letters and numbers.

Included is a sample ActiveRecord class (MyTable.php).

Sort file (with unique option) (JavaScript)

2010-05-30T21:47:36-07:00

JavaScript recipe 577247 by Glenn Jenkins (file, komodo, sort, unique).

This will sort the lines in the current document into alphabetical order. It doesn't apply any special rule (so 5 will come after 42).

On running, it asks if you want a unique sort (Cancel for no, Ok for yes), in which case it'll remove duplicate lines.

Sets with a custom equality/uniqueness function (Python)

2009-10-29T21:08:22-07:00

Python recipe 576932 by Gabriel Genellina (abstract_base_class, mutableset, set, unique). Revision 4.

The builtin set and frozenset types are based on object equality; they call __eq__ to determine whether an object is a member of the set or not. But there are cases when one needs a set of objects that are compared by other means, apart from the default __eq__ function. There are several ways to achieve that; this recipe presents two classes, FrozenKeyedSet and KeyedSet, that take an additional function key which is used to determine membership and uniqueness. Given two objects which return the same value for key, only one of them will be in the set.

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.