Source code for docarray.document.mixins.featurehash

import hashlib
import json
from typing import Tuple, TYPE_CHECKING

import numpy as np

    from ...typing import T

[docs]class FeatureHashMixin: """Provide helper functions for feature hashing."""
[docs] def embed_feature_hashing( self: 'T', n_dim: int = 256, sparse: bool = False, fields: Tuple[str, ...] = ('text', 'tags'), max_value: int = 1_000_000, ) -> 'T': """Convert an arbitrary set of attributes into a fixed-dimensional matrix using the hashing trick. :param n_dim: the dimensionality of each document in the output embedding. Small numbers of features are likely to cause hash collisions, but large numbers will cause larger overall parameter dimensions. :param sparse: whether the resulting feature matrix should be a sparse csr_matrix or dense ndarray. Note that this feature requires ``scipy`` :param fields: which attributes to be considered as for feature hashing. """ if sparse: from scipy.sparse import csr_matrix idxs, data = [], [] # sparse table = np.zeros(n_dim) # dense for f in fields: if 'text' in fields: all_tokens = self.get_vocabulary(('text',)) for f_id, val in all_tokens.items(): _hash_column(f_id, val, n_dim, max_value, idxs, data, table) if 'tags' in fields: for k, v in self.tags.items(): _hash_column(k, v, n_dim, max_value, idxs, data, table) v = getattr(self, f, None) if v: _hash_column(f, v, n_dim, max_value, idxs, data, table) if sparse: self.embedding = csr_matrix((data, zip(*idxs)), shape=(1, n_dim)) else: self.embedding = table return self
def _hash_column(col_name, col_val, n_dim, max_value, idxs, data, table): h = _any_hash(col_name) col_val = _any_hash(col_val) % max_value col = h % n_dim idxs.append((0, col)) data.append(np.sign(h) * col_val) table[col] += np.sign(h) * col_val def _any_hash(v): if not v: # ignore it when the parameter is empty return 0 elif isinstance(v, (tuple, dict, list, str)): if isinstance(v, str): v = v.strip() if v.lower() in {'true', 'yes'}: # parse boolean parameter return 1 if v.lower() in {'false', 'no'}: return 0 else: v = json.dumps(v, sort_keys=True) return int(hashlib.md5(str(v).encode('utf-8')).hexdigest(), base=16) else: try: return int(v) # parse int parameter except ValueError: try: return float(v) # parse float parameter except ValueError: return 0 # unable to hash