Popular recipes tagged "first"

Follow Sets Construction (Python)

2015-12-22T10:49:21-08:00

Python recipe 579140 by Narayana Chikkam (cfg, first, follow, nullable). Revision 2.

Language Processors: FOLLOW(A) = {t | (t is a terminal and S ⇒+ α A t β) or (t is EOF and S ⇒∗ αA)}

Bash completed man and info pages generation (Python)

2011-08-24T03:14:13-07:00

Python recipe 577854 by Josh D (a, all, and, bash, be, command, completed, consume, file, first, generation, get, in, info, line, man, modify, must, only, pages, possibilties, possiblities, py, python, run, script, so, tab, terminal, the, this, to). Revision 6.

The script it self is very self explaining - the task is simple. *NIX only unless with cygwin perhaps?

To start this open a terminal and strike the "Tab" key to get all possibilities (strike y, and strike the space key alot). Select all then Copy and save in "comms.txt" Modify the file so ONLY the possiblities consume a line; no prompts or extra newlines. (first line must be a command, the last line must be a command)

Save the file ("~/Documents/bashing/comms.txt" is my path) then run this script in "~/Documents/bashing/".

This generates two (2) files: "bash_help_man.sh", "bash_help_info.sh".

Then it runs these files: "bash bash_help_man.sh", "bash bash_help_info.sh".

This produces 2 files for every command (every line) in "comms.txt". All manpages are wrote in "mans/", all infopages are wrote in "infos/"

There is now alot of files to read and organize; lets separate these by size. Directories are under1kb, under2kb, etc.

Once complete do as you wish the files less than 128 kb; these files are COPIED into there new respective home, I repeat COPIED.

The files 128 kb and higher ARE NOT copied to anywhere!

Simple graph algorithms with a modular design (Python)

2011-04-21T13:40:32-07:00

Python recipe 577668 by jimmy2times (algorithms, breadth, depth, directed, first, graph, object, oriented, python, search, theory, undirected, visit). Revision 7.

The purpose of this recipe is to look at algorithmic graph theory from an object-oriented perspective.

A graph is built on top of a dictionary indexed by its vertices, each item being the set of neighbours of the key vertex. This ensures that iterating through the neighbours of a vertex is still efficient in sparse graphs (as with adjacency lists) while at the same time checking for adjacency is expected constant-time (as with the adjacency matrix).

Any valid class of graph must implement the interface defined by AbstractGraph.

A generic search algorithm takes as input a graph, source and target vertices and a queue. A queue must implement the methods Q.get(), Q.put() and Q.empty() in such a way to get the desired order in visiting the vertices.

Given this pattern, breadth-first and depth-first search are essentially defined by the corresponding expansion policies: the first one uses an actual FIFO queue, the second one a LIFO queue (or stack).