Introduce Chars

This improves the implementation by introducing a class to manage the characters

src/ilp_keyboard_layout_optimization/receive_data.py

@@ -120,11 +120,10 @@ class CharProbs:
                     row["bigram"][0] in self.chars and row["bigram"][1] in self.chars
                 ):
                     bi_probs[row["bigram"]] = absolute_count
-        total_sum = sum(bi_probs.values())
-        assert total_sum > 0
-        normalizer = 100 / total_sum
+        absolute_sum = sum(bi_probs.values())
         for character, count in bi_probs.items():
-            bi_probs[character] = count / normalizer
+            bi_probs[character] = count / absolute_sum
+        assert round(sum(bi_probs.values()), 8) == 1
         assert len(bi_probs) == reader.line_num or len(bi_probs) <= comb(
             reader.line_num, 2
         )