Merge pull request #117 from x-tabdeveloping/optimization

Auto n_components for multiple topic models

Author: x-tabdeveloping

docs/Topeax.md

@@ -0,0 +1,18 @@
+# Topeax
+
+Topeax is a probabilistic topic model based on the Peax clustering model, which finds topics based on peaks in point density in the embedding space.
+It can recover the number of topics automatically.
+
+<br>
+<figure>
+  <img src="../images/peax.png" width="100%" style="margin-left: auto;margin-right: auto;">
+  <figcaption>Schematic overview of the steps of the Peax clustering algorithm</figcaption>
+</figure>
+
+:warning: **This part of the documentation is still under construction, as more details and a paper are on their way.** :warning:
+
+## API Reference
+
+::: turftopic.models.topeax.Topeax
+
+::: turftopic.models.topeax.Peax

docs/images/peax.png

@@ -9,7 +9,7 @@ profile = "black"
 
 [project]
 name = "turftopic"
-version = "0.19.1"
+version = "0.20.0"
 description = "Topic modeling with contextual representations from sentence transformers."
 authors = [
    { name = "Márton Kardos <[email protected]>", email = "[email protected]" }

pyproject.toml

@@ -7,6 +7,7 @@
 from turftopic.models.fastopic import FASTopic
 from turftopic.models.gmm import GMM
 from turftopic.models.keynmf import KeyNMF
+from turftopic.models.topeax import Topeax
 from turftopic.serialization import load_model
 
 try:
@@ -20,6 +21,7 @@
     "ClusteringTopicModel",
     "SemanticSignalSeparation",
     "GMM",
+    "Topeax",
     "KeyNMF",
     "AutoEncodingTopicModel",
     "ContextualModel",

turftopic/__init__.py

@@ -1,6 +1,10 @@
 import itertools
 from typing import Iterable, List
 
+import numpy as np
+import torch
+from tqdm import trange
+
 
 def batched(iterable, n: int) -> Iterable[List[str]]:
     "Batch data into tuples of length n. The last batch may be shorter."
@@ -10,3 +14,47 @@ def batched(iterable, n: int) -> Iterable[List[str]]:
     it = iter(iterable)
     while batch := list(itertools.islice(it, n)):
         yield batch
+
+
+def encode_chunks(
+    encoder,
+    sentences,
+    batch_size=64,
+    window_size=50,
+    step_size=40,
+    return_chunks=False,
+    show_progress_bar=False,
+):
+    chunks = []
+    chunk_embeddings = []
+    for start_index in trange(
+        0,
+        len(sentences),
+        batch_size,
+        desc="Encoding batches...",
+        disable=not show_progress_bar,
+    ):
+        batch = sentences[start_index : start_index + batch_size]
+        features = encoder.tokenize(batch)
+        with torch.no_grad():
+            output_features = encoder.forward(features)
+        n_tokens = output_features["attention_mask"].sum(axis=1)
+        for i_doc in range(len(batch)):
+            for chunk_start in range(0, n_tokens[i_doc], step_size):
+                chunk_end = min(chunk_start + window_size, n_tokens[i_doc])
+                _emb = output_features["token_embeddings"][
+                    i_doc, chunk_start:chunk_end, :
+                ].mean(axis=0)
+                chunk_embeddings.append(_emb)
+                if return_chunks:
+                    chunks.append(
+                        encoder.tokenizer.decode(
+                            features["input_ids"][i_doc, chunk_start:chunk_end]
+                        )
+                        .replace("[CLS]", "")
+                        .replace("[SEP]", "")
+                    )
+    if not return_chunks:
+        chunks = None
+    chunk_embeddings = np.stack(chunk_embeddings)
+    return chunk_embeddings, chunks

turftopic/encoders/utils.py

@@ -2,7 +2,8 @@
 import warnings
 from collections import defaultdict
 from datetime import datetime
-from typing import Iterable, Literal, Optional
+from functools import partial
+from typing import Iterable, Literal, Optional, Union
 
 import igraph as ig
 import numpy as np
@@ -21,6 +22,10 @@
 from sklearn.utils.validation import check_non_negative
 
 from turftopic.base import Encoder
+from turftopic.optimization import (
+    decomposition_gaussian_bic,
+    optimize_n_components,
+)
 
 NOT_MATCHING_ERROR = (
     "Document embedding dimensionality ({n_dims}) doesn't match term embedding dimensionality ({n_word_dims}). "
@@ -242,7 +247,7 @@ def batch_extract_keywords(
 class KeywordNMF:
     def __init__(
         self,
-        n_components: int,
+        n_components: Union[int, Literal["auto"]],
         seed: Optional[int] = None,
         top_n: Optional[int] = None,
     ):
@@ -318,6 +323,15 @@ def vectorize(
 
     def fit_transform(self, keywords: list[dict[str, float]]) -> np.ndarray:
         X = self.vectorize(keywords, fitting=True)
+        if self.n_components == "auto":
+            # Finding N components with BIC
+            bic_fn = partial(
+                decomposition_gaussian_bic,
+                decomp_class=NMF,
+                X=X,
+            )
+            n_components = optimize_n_components(bic_fn, min_n=1, verbose=True)
+            self.n_components = n_components
         check_non_negative(X, "NMF (input X)")
         W, H = _initialize_nmf(X, self.n_components, random_state=self.seed)
         W, H, self.n_iter = NMF(
@@ -339,6 +353,10 @@ def transform(self, keywords: list[dict[str, float]]):
         return W.astype(X.dtype)
 
     def partial_fit(self, keyword_batch: list[dict[str, float]]):
+        if self.n_components == "auto":
+            raise ValueError(
+                "Cannot infer number of components with BIC when online fitting the model."
+            )
         X = self.vectorize(keyword_batch, fitting=True)
         try:
             check_non_negative(X, "NMF (input X)")
@@ -365,6 +383,15 @@ def fit_transform_dynamic(
         n_bins = len(time_bin_edges) - 1
         document_term_matrix = self.vectorize(keywords, fitting=True)
         check_non_negative(document_term_matrix, "NMF (input X)")
+        if self.n_components == "auto":
+            # Finding N components with BIC
+            bic_fn = partial(
+                decomposition_gaussian_bic,
+                decomp_class=NMF,
+                X=X,
+            )
+            n_components = optimize_n_components(bic_fn, verbose=True)
+            self.n_components = n_components
         document_topic_matrix, H = _initialize_nmf(
             document_term_matrix,
             self.n_components,