Source code for lightwood.encoder.text.short

from typing import List
import torch
from lightwood.encoder import BaseEncoder
from lightwood.encoder.categorical import CategoricalAutoEncoder
from lightwood.helpers.text import tokenize_text
from lightwood.helpers.torch import concat_vectors_and_pad, average_vectors
import pandas as pd


[docs]class ShortTextEncoder(BaseEncoder): def __init__(self, is_target=False, mode=None): """ :param is_target: :param mode: None or "concat" or "mean". When None, it will be set automatically based on is_target: (is_target) -> 'concat' (not is_target) -> 'mean' """ super().__init__(is_target) if mode is None: if is_target: self._mode = 'concat' else: self._mode = 'mean' else: if mode not in ['concat', 'mean']: self._unexpected_mode() if is_target and mode != 'concat': raise ValueError('mode must be "concat" when is_target=True') self._mode = mode # Defined in self.prepare() self._combine_fn = None self.max_words_per_sent = None self.cae = CategoricalAutoEncoder(is_target=is_target, max_encoded_length=100) self.is_prepared = False def _unexpected_mode(self): raise ValueError('unexpected combine value (must be "mean" or "concat")') # defining both of these as normal functions because pickle can't deal with lambdas def _combine_concat(self, vecs): return concat_vectors_and_pad(vecs, self.max_words_per_sent) def _combine_mean(self, vecs): return average_vectors(vecs)
[docs] def prepare(self, priming_data): no_null_sentences = (x if x is not None else '' for x in priming_data) unique_tokens = set() max_words_per_sent = 0 for sent in no_null_sentences: tokens = tokenize_text(sent) max_words_per_sent = max(max_words_per_sent, len(tokens)) for tok in tokens: unique_tokens.add(tok) self.cae.prepare(pd.Series(list(unique_tokens)), pd.Series([])) if self._mode == 'concat': self.max_words_per_sent = max_words_per_sent self._combine_fn = self._combine_concat elif self._mode == 'mean': self._combine_fn = self._combine_mean else: self._unexpected_mode() self.is_prepared = True encoded = self.encode([priming_data[0]]) self.output_size = len(encoded[0])
[docs] def encode(self, column_data: List[str]) -> torch.Tensor: no_null_sentences = (x if x is not None else '' for x in column_data) output = [] for sent in no_null_sentences: tokens = tokenize_text(sent) encoded_words = self.cae.encode(tokens) encoded_sent = self._combine_fn(encoded_words) output.append(torch.Tensor(encoded_sent)) output = torch.stack(output) return output
[docs] def decode(self, vectors): if self._mode == 'concat': vec_size = self.cae.output_size output = [] for vec in vectors: viewed_vec = vec.view(-1, vec_size) # Find index of first padding vector for index, v in enumerate(viewed_vec): if v.abs().sum() == 0: break else: index = viewed_vec.size(0) out = self.cae.decode( viewed_vec[:index] ) output.append(out) return output elif self._mode == 'mean': raise ValueError('decode is only defined for mode="concat"') else: self._unexpected_mode()