Upload segmentation.py

segmentation.py

@@ -0,0 +1,96 @@
+import attr
+import pandas as pd
+import numpy as np
+from .utils import load_sentence_transformer, load_spacy
+from nltk.tokenize.texttiling import TextTilingTokenizer
+from sklearn.metrics.pairwise import cosine_similarity
+
+model = load_sentence_transformer()
+nlp = load_spacy()
+
+
+@attr.s
+class SemanticTextSegmentation:
+
+    """
+    Segment a call transcript based on topics discussed in the call using
+    TextTilling with Sentence Similarity via sentence transformer.
+
+    Paramters
+    ---------
+    data: pd.Dataframe
+        Pass the trascript in the dataframe format
+
+    utterance: str
+        pass the column name which represent utterance in transcript dataframe
+
+    """
+
+    data = attr.ib()
+    utterance = attr.ib(default='utterance')
+
+    def __attrs_post_init__(self):
+        columns = self.data.columns.tolist()
+
+    def get_segments(self, threshold=0.7):
+        """
+        returns the transcript segments computed with texttiling and sentence-transformer.
+
+        Paramters
+        ---------
+        threshold: float
+            sentence similarity threshold. (used to merge the sentences into coherant segments)
+
+        Return
+        ------
+        new_segments: list
+            list of segments        
+        """
+        segments = self._text_tilling()
+        merge_index = self._merge_segments(segments, threshold)
+        new_segments = []
+        for i in merge_index:
+            seg = ' '.join([segments[_] for _ in i])
+            new_segments.append(seg)
+        return new_segments
+
+    def _merge_segments(self, segments, threshold):
+        segment_map = [0]
+        for index, (text1, text2) in enumerate(zip(segments[:-1], segments[1:])):
+            sim = self._get_similarity(text1, text2)
+            if sim >= threshold:
+                segment_map.append(0)
+            else:
+                segment_map.append(1)
+        return self._index_mapping(segment_map)
+
+    def _index_mapping(self, segment_map):
+        index_list = []
+        temp = []
+        for index, i in enumerate(segment_map):
+            if i == 1:
+                index_list.append(temp)
+                temp = [index]
+            else:
+                temp.append(index)
+        index_list.append(temp)
+        return index_list
+
+    def _get_similarity(self, text1, text2):
+        sentence_1 = [i.text.strip()
+                      for i in nlp(text1).sents if len(i.text.split(' ')) > 1]
+        sentence_2 = [i.text.strip()
+                      for i in nlp(text2).sents if len(i.text.split(' ')) > 2]
+        embeding_1 = model.encode(sentence_1)
+        embeding_2 = model.encode(sentence_2)
+        embeding_1 = np.mean(embeding_1, axis=0).reshape(1, -1)
+        embeding_2 = np.mean(embeding_2, axis=0).reshape(1, -1)
+        sim = cosine_similarity(embeding_1, embeding_2)
+        return sim
+
+    def _text_tilling(self):
+        tt = TextTilingTokenizer(w=15, k=10)
+        text = '\n\n\t'.join(self.data[self.utterance].tolist())
+        segment = tt.tokenize(text)
+        segment = [i.replace("\n\n\t", ' ') for i in segment]
+        return segment