[dwg] added

dwg/README.md

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+# dwg
+
+dwg is a script that converts coordinates into four words and back, using a dictionary like Diceware.
+
+## Usage
+
+```
+$ echo 55.5455 35.5434 | dwg.py dict.txt
+supra skate oral canal
+$ echo supra skate oral canal | dwg.py -d dict.txt
+55.54550065 35.5433973
+```
+
+## Dictionaries
+
+Reinhold's original [Diceware](https://theworld.com/~reinhold/diceware.wordlist.asc) dictionary is included as dict.txt, with numbers
+and the PGP signature trimmed off. Any other newline-delimited text file will work as a dictionary file.

dwg/dwg.py

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+#!/usr/bin/env python3
+
+# See LICENSE file for copyright and license details.
+
+import argparse
+
+parser = argparse.ArgumentParser(
+        description='''A script to encode coordinates from stdin to 4 words, or decode them.''')
+parser.add_argument("dictionary", type=str,
+help="The dictionary file to use. Each line is used as a word.")
+parser.add_argument("--decode", "-d", action="store_true",
+        help="Decode 4 words from stdin to coordinates")
+
+args = parser.parse_args()
+
+fp = open(args.dictionary, "r")
+lines = fp.readlines()
+# -1 for 0 indexing
+nl = len(lines) - 1
+
+if nl <= 0:
+    raise(EOFError("Dictionary needs to have at least 2 words"))
+
+def gw(ln):
+    # Get a word from an index
+    return lines[ln][:-1]
+
+def gln(word):
+    # Get the index from a word
+    for i, line in enumerate(lines):
+        if line.strip() == word.strip():
+            return i
+
+    raise(ValueError(f"No match for word {word} in {args.dictionary}."))
+
+if not args.decode:
+    lat, long = [float(i) for i in input().split()]
+
+    if lat < -90 or lat > 90:
+        raise(ValueError(f"Invalid latitude {lat}"))
+    if long < -90 or long > 90:
+        raise(ValueError(f"Invalid longitude {long}"))
+
+    # Map to positive numbers
+    lat += 90
+    long += 180
+
+    latV = lat/180*nl**2
+    longV = long/360*nl**2
+
+    print(gw(round(latV // nl)), end=" ")
+    print(gw(round(latV % nl)), end=" ")
+    print(gw(round(longV // nl)), end=" ")
+    print(gw(round(longV % nl)))
+
+else:
+    words = input().split()
+    lat = (gln(words[0]) * nl + gln(words[1])) / nl ** 2 * 180 - 90
+    lon = (gln(words[2]) * nl + gln(words[3])) / nl ** 2 * 360 - 180
+
+    print('{:.10}'.format(round(lat, 8)), end=" ")
+    print('{:.9}'.format(round(lon, 8)))