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Skraflhjálp (SCRABBLE(tm) Helper)

English summary

This set of Python 3.x programs and modules implements a dictionary and word permutation engine that is the core of an Icelandic SCRABBLE(tm) Helper website.

The web and its engine are helpful for SCRABBLE(tm) players, crossword enthusiasts and others - including programmers - who are interested in fast and flexible dictionary implementation, for Icelandic and other languages.

The software uses a DAWG (Directed Acyclic Word Graph, also called Deterministic Acyclic Finite State Automaton, DAFSA or Minimal Acyclic Finite State Automaton, MA-FSA) to represent the dictionary. This enables very fast lookup, pattern matching and permutation, even with wildcards and long letter sequences.

The DAWG is pre-built from plain text word lists, compacted on-the-fly and stored in a compact - yet Pythonistic - text-based form.

The algorithm for building an optimal DAWG from lists of valid words is based on the theory of Daciuk et al, with reference to Steve Hanov's implementation (and a nod to ftbe's Go code on GitHub). However it optimizes further than Hanov does by collapsing chains of nodes connected by single edges into multi-letter edges, reducing the node count significantly.

At run time, permutations are found in an efficient way, even in the presence of wildcards (blank tiles), by direct traversal of the graph. For details see the dawgbuilder.py and dawgdictionary.py files.

The code builds a 103,000 node DAWG for the Icelandic language, 2.6 million words, in about 38 seconds (PyPy) / 160 seconds (CPython) on a medium-powered Windows desktop PC. The resulting graph structure is stored in a 3,466 KB file and takes under 4 seconds to load into memory.

For English, it converts the 178,691 words of the SCRABBLE(tm) Tournament World List v6 (TWL06) into a graph of 29,691 nodes in under 3 seconds (PyPy) / 10 seconds (CPython). The resulting .dawg.text file is 772 KB.

Generation of all permutations of a 7-letter SCRABBLE(tm) rack, as well as combinations of the rack with one additional letter, typically takes 30-70 milliseconds (CPython).

SCRABBLE is a registered trademark. This software or its author are in no way affiliated with or endorsed by the owners or licensees of the SCRABBLE trademark.

Íslenskt yfirlit

Vefur sem hjálpar skröflurum að finna orð í rekkanum og tengja þau við stafi sem fyrir eru.

Vefurinn er byggður á Python 3 og notar Flask undirforritasafnið, þar með talið Jinja2 sniðmátakerfið (templates).

Hann notar Bootstrap CSS-safnið fyrir viðmót og þægilega aðlögun að mismunandi skjám, þ.e. síma, spjaldtölvu eða borðtölvu.

Vefinn má nálgast á https://skraflhjalp.appspot.com

Notkun vefsins

Ef farið er inn á vefslóðina / kemur upp aðalsíða Skraflhjálpar. Slóðin /help gefur hjálparsíðu.

Til að keyra á eigin tölvu

Settu upp Python 3.11.

Sæktu þetta Git safn:

git clone https://github.com/vthorsteinsson/skrafl.git

Sæktu undirforritasöfn.

cd skrafl
pip install -r requirements.txt

Keyra má vefþjón Skraflhjálpar í þróunarham beint frá skipanalínu.
```
python skrafl.py
```
Nálgast má vefinn á vefrápara:

Í skýinu á appspot.com https://skraflhjalp.appspot.com

Venjuleg Python 3 uppsetning með Flask/Werkzeug http://localhost:3000

Ef óskað er, má breyta port-númerinu neðst í skránni skrafl.py.

Höfundur

Vilhjálmur Þorsteinsson