Add thai keyboard distance

pythainlp/util/__init__.py

@@ -32,6 +32,7 @@
     "text_to_arabic_digit",
     "text_to_thai_digit",
     "thai_digit_to_arabic_digit",
+    "thai_keyboard_dist",
     "thai_strftime",
     "thai_time",
     "thai_to_eng",
@@ -54,7 +55,11 @@
     text_to_thai_digit,
     thai_digit_to_arabic_digit,
 )
-from pythainlp.util.keyboard import eng_to_thai, thai_to_eng
+from pythainlp.util.keyboard import (
+    eng_to_thai,
+    thai_keyboard_dist,
+    thai_to_eng,
+)
 from pythainlp.util.keywords import find_keyword, rank
 from pythainlp.util.normalize import (
     delete_tone,

pythainlp/util/keyboard.py

@@ -103,6 +103,20 @@
 EN_TH_TRANSLATE_TABLE = str.maketrans(EN_TH_KEYB_PAIRS)
 TH_EN_TRANSLATE_TABLE = str.maketrans(TH_EN_KEYB_PAIRS)
 
+TIS_820_2538 = [
+  "-", "ๅ", "/", "_", "ภ", "ถ", "ุ", "ึ", "ค", "ต", "จ", "ข", "ช",
+  "ๆ", "ไ", "ำ", "พ", "ะ", "ั", "ี", "ร", "น", "ย", "บ", "ล", "ฃ",
+  "ฟ", "ห", "ก", "ด", "เ", "้", "่", "า", "ส", "ว", "ง",
+  "ผ", "ป", "แ", "อ", "ิ", "ื", "ท", "ม", "ใ", "ฝ"
+]
+
+TIS_820_2538_SHIFT = [
+  "%", "+", "๑", "๒", "๓", "๔", "ู", "฿", "๕", "๖", "๗", "๘", "๙",
+  "๐", "\"", "ฎ", "ฑ", "ธ", "ํ", "๊", "ณ", "ฯ", "ญ", "ฐ", ",", "ฅ",
+  "ฤ", "ฆ", "ฏ", "โ", "ฌ", "็", "๋", "ษ", "ศ", "ซ", ".",
+  "(", ")", "ฉ", "ฮ", "ฺ", "์", "?", "ฒ", "ฬ", "ฦ"
+]
+
 
 def eng_to_thai(text: str) -> str:
     """
@@ -148,3 +162,42 @@ def thai_to_eng(text: str) -> str:
         # output: 'Bank of Thailand'
     """
     return text.translate(TH_EN_TRANSLATE_TABLE)
+
+
+def thai_keyboard_dist(c1: str, c2: str, shift_dist: float = 0.0) -> float:
+    """
+    Calculate euclidean distance between two Thai characters
+
+    :param str c1: first character
+    :param str c2: second character
+    :param str shift_dist: return value if they're shifted
+    :return: euclidean distance between two characters
+    :rtype: float
+
+    :Example:
+
+        from pythainlp.util import thai_keyboard_dist
+        thai_keyboard_dist("ฟ", "ฤ")
+        # output: 0.0
+        thai_keyboard_dist("ฟ", "ห")
+        # output: 1.0
+        thai_keyboard_dist("ฟ", "ก")
+        # output: 2.0
+        thai_keyboard_dist("ฟ", "ฤ", 0.5)
+        # output: 0.5
+    """
+    def get_char_coord(ch: str, layouts=[TIS_820_2538, TIS_820_2538_SHIFT]):
+        for layout in layouts:
+            for row in layout:
+                if ch in row:
+                    r = layout.index(row)
+                    c = row.index(ch)
+                    return (r, c)
+        raise ValueError(c + " not found in given keyboard layout")
+
+    coord1 = get_char_coord(c1)
+    coord2 = get_char_coord(c2)
+    distance = ((coord1[0] - coord2[0])**2 + (coord1[1] - coord2[1])**2)**(0.5)
+    if distance == 0 and c1 != c2:
+        return shift_dist
+    return distance

tests/test_util.py

@@ -43,6 +43,7 @@
     time_to_thaiword,
     thai_to_eng,
     thaiword_to_num,
+    thai_keyboard_dist,
 )
 
 
@@ -156,6 +157,14 @@ def test_rank(self):
             rank(["แมว", "คน", "แมว"], exclude_stopwords=True)
         )
 
+    # ### pythainlp.util.keyboard
+
+    def test_thai_keyboard_dist(self):
+        self.assertEqual(thai_keyboard_dist("ฟ", "ฤ"), 0.0)
+        self.assertEqual(thai_keyboard_dist("ฟ", "ห"), 1.0)
+        self.assertEqual(thai_keyboard_dist("ฟ", "ก"), 2.0)
+        self.assertEqual(thai_keyboard_dist("ฟ", "ฤ", 0.5), 0.5)
+
     # ### pythainlp.util.date
 
     def test_date(self):