mirror of https://github.com/explosion/spaCy.git
826 lines
26 KiB
Python
826 lines
26 KiB
Python
# coding: utf8
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from __future__ import unicode_literals
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import numpy
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from thinc.v2v import Model, Maxout, Softmax, Affine, ReLu
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from thinc.i2v import HashEmbed, StaticVectors
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from thinc.t2t import ExtractWindow, ParametricAttention
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from thinc.t2v import Pooling, sum_pool, mean_pool
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from thinc.misc import Residual
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from thinc.misc import LayerNorm as LN
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from thinc.misc import FeatureExtracter
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from thinc.api import add, layerize, chain, clone, concatenate, with_flatten
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from thinc.api import with_getitem, flatten_add_lengths
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from thinc.api import uniqued, wrap, noop
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from thinc.api import with_square_sequences
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from thinc.linear.linear import LinearModel
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from thinc.neural.ops import NumpyOps, CupyOps
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from thinc.neural.util import get_array_module
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from thinc.neural.optimizers import Adam
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from thinc import describe
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from thinc.describe import Dimension, Synapses, Biases, Gradient
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from thinc.neural._classes.affine import _set_dimensions_if_needed
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import thinc.extra.load_nlp
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from .attrs import ID, ORTH, LOWER, NORM, PREFIX, SUFFIX, SHAPE
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from .errors import Errors, user_warning, Warnings
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from . import util
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try:
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import torch.nn
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from thinc.extra.wrappers import PyTorchWrapperRNN
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except ImportError:
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torch = None
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VECTORS_KEY = "spacy_pretrained_vectors"
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def cosine(vec1, vec2):
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xp = get_array_module(vec1)
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norm1 = xp.linalg.norm(vec1)
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norm2 = xp.linalg.norm(vec2)
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if norm1 == 0.0 or norm2 == 0.0:
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return 0
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else:
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return vec1.dot(vec2) / (norm1 * norm2)
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def create_default_optimizer(ops, **cfg):
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learn_rate = util.env_opt("learn_rate", 0.001)
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beta1 = util.env_opt("optimizer_B1", 0.9)
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beta2 = util.env_opt("optimizer_B2", 0.999)
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eps = util.env_opt("optimizer_eps", 1e-8)
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L2 = util.env_opt("L2_penalty", 1e-6)
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max_grad_norm = util.env_opt("grad_norm_clip", 1.0)
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optimizer = Adam(ops, learn_rate, L2=L2, beta1=beta1, beta2=beta2, eps=eps)
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optimizer.max_grad_norm = max_grad_norm
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optimizer.device = ops.device
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return optimizer
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@layerize
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def _flatten_add_lengths(seqs, pad=0, drop=0.0):
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ops = Model.ops
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lengths = ops.asarray([len(seq) for seq in seqs], dtype="i")
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def finish_update(d_X, sgd=None):
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return ops.unflatten(d_X, lengths, pad=pad)
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X = ops.flatten(seqs, pad=pad)
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return (X, lengths), finish_update
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def _zero_init(model):
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def _zero_init_impl(self, *args, **kwargs):
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self.W.fill(0)
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model.on_init_hooks.append(_zero_init_impl)
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if model.W is not None:
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model.W.fill(0.0)
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return model
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def with_cpu(ops, model):
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"""Wrap a model that should run on CPU, transferring inputs and outputs
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as necessary."""
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model.to_cpu()
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def with_cpu_forward(inputs, drop=0.0):
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cpu_outputs, backprop = model.begin_update(_to_cpu(inputs), drop=drop)
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gpu_outputs = _to_device(ops, cpu_outputs)
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def with_cpu_backprop(d_outputs, sgd=None):
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cpu_d_outputs = _to_cpu(d_outputs)
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return backprop(cpu_d_outputs, sgd=sgd)
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return gpu_outputs, with_cpu_backprop
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return wrap(with_cpu_forward, model)
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def _to_cpu(X):
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if isinstance(X, numpy.ndarray):
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return X
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elif isinstance(X, tuple):
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return tuple([_to_cpu(x) for x in X])
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elif isinstance(X, list):
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return [_to_cpu(x) for x in X]
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elif hasattr(X, "get"):
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return X.get()
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else:
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return X
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def _to_device(ops, X):
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if isinstance(X, tuple):
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return tuple([_to_device(ops, x) for x in X])
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elif isinstance(X, list):
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return [_to_device(ops, x) for x in X]
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else:
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return ops.asarray(X)
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class extract_ngrams(Model):
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def __init__(self, ngram_size, attr=LOWER):
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Model.__init__(self)
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self.ngram_size = ngram_size
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self.attr = attr
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def begin_update(self, docs, drop=0.0):
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batch_keys = []
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batch_vals = []
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for doc in docs:
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unigrams = doc.to_array([self.attr])
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ngrams = [unigrams]
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for n in range(2, self.ngram_size + 1):
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ngrams.append(self.ops.ngrams(n, unigrams))
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keys = self.ops.xp.concatenate(ngrams)
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keys, vals = self.ops.xp.unique(keys, return_counts=True)
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batch_keys.append(keys)
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batch_vals.append(vals)
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# The dtype here matches what thinc is expecting -- which differs per
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# platform (by int definition). This should be fixed once the problem
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# is fixed on Thinc's side.
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lengths = self.ops.asarray(
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[arr.shape[0] for arr in batch_keys], dtype=numpy.int_
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)
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batch_keys = self.ops.xp.concatenate(batch_keys)
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batch_vals = self.ops.asarray(self.ops.xp.concatenate(batch_vals), dtype="f")
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return (batch_keys, batch_vals, lengths), None
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@describe.on_data(
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_set_dimensions_if_needed, lambda model, X, y: model.init_weights(model)
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)
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@describe.attributes(
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nI=Dimension("Input size"),
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nF=Dimension("Number of features"),
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nO=Dimension("Output size"),
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nP=Dimension("Maxout pieces"),
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W=Synapses("Weights matrix", lambda obj: (obj.nF, obj.nO, obj.nP, obj.nI)),
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b=Biases("Bias vector", lambda obj: (obj.nO, obj.nP)),
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pad=Synapses(
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"Pad",
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lambda obj: (1, obj.nF, obj.nO, obj.nP),
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lambda M, ops: ops.normal_init(M, 1.0),
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),
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d_W=Gradient("W"),
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d_pad=Gradient("pad"),
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d_b=Gradient("b"),
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)
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class PrecomputableAffine(Model):
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def __init__(self, nO=None, nI=None, nF=None, nP=None, **kwargs):
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Model.__init__(self, **kwargs)
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self.nO = nO
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self.nP = nP
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self.nI = nI
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self.nF = nF
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def begin_update(self, X, drop=0.0):
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Yf = self.ops.gemm(
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X, self.W.reshape((self.nF * self.nO * self.nP, self.nI)), trans2=True
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)
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Yf = Yf.reshape((Yf.shape[0], self.nF, self.nO, self.nP))
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Yf = self._add_padding(Yf)
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def backward(dY_ids, sgd=None):
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dY, ids = dY_ids
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dY, ids = self._backprop_padding(dY, ids)
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Xf = X[ids]
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Xf = Xf.reshape((Xf.shape[0], self.nF * self.nI))
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self.d_b += dY.sum(axis=0)
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dY = dY.reshape((dY.shape[0], self.nO * self.nP))
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Wopfi = self.W.transpose((1, 2, 0, 3))
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Wopfi = self.ops.xp.ascontiguousarray(Wopfi)
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Wopfi = Wopfi.reshape((self.nO * self.nP, self.nF * self.nI))
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dXf = self.ops.gemm(dY.reshape((dY.shape[0], self.nO * self.nP)), Wopfi)
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# Reuse the buffer
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dWopfi = Wopfi
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dWopfi.fill(0.0)
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self.ops.gemm(dY, Xf, out=dWopfi, trans1=True)
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dWopfi = dWopfi.reshape((self.nO, self.nP, self.nF, self.nI))
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# (o, p, f, i) --> (f, o, p, i)
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self.d_W += dWopfi.transpose((2, 0, 1, 3))
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if sgd is not None:
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sgd(self._mem.weights, self._mem.gradient, key=self.id)
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return dXf.reshape((dXf.shape[0], self.nF, self.nI))
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return Yf, backward
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def _add_padding(self, Yf):
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Yf_padded = self.ops.xp.vstack((self.pad, Yf))
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return Yf_padded
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def _backprop_padding(self, dY, ids):
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# (1, nF, nO, nP) += (nN, nF, nO, nP) where IDs (nN, nF) < 0
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mask = ids < 0.0
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mask = mask.sum(axis=1)
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d_pad = dY * mask.reshape((ids.shape[0], 1, 1))
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self.d_pad += d_pad.sum(axis=0)
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return dY, ids
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@staticmethod
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def init_weights(model):
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"""This is like the 'layer sequential unit variance', but instead
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of taking the actual inputs, we randomly generate whitened data.
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Why's this all so complicated? We have a huge number of inputs,
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and the maxout unit makes guessing the dynamics tricky. Instead
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we set the maxout weights to values that empirically result in
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whitened outputs given whitened inputs.
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"""
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if (model.W ** 2).sum() != 0.0:
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return
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ops = model.ops
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xp = ops.xp
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ops.normal_init(model.W, model.nF * model.nI, inplace=True)
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ids = ops.allocate((5000, model.nF), dtype="f")
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ids += xp.random.uniform(0, 1000, ids.shape)
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ids = ops.asarray(ids, dtype="i")
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tokvecs = ops.allocate((5000, model.nI), dtype="f")
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tokvecs += xp.random.normal(loc=0.0, scale=1.0, size=tokvecs.size).reshape(
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tokvecs.shape
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)
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def predict(ids, tokvecs):
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# nS ids. nW tokvecs. Exclude the padding array.
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hiddens = model(tokvecs[:-1]) # (nW, f, o, p)
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vectors = model.ops.allocate((ids.shape[0], model.nO * model.nP), dtype="f")
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# need nS vectors
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hiddens = hiddens.reshape(
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(hiddens.shape[0] * model.nF, model.nO * model.nP)
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)
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model.ops.scatter_add(vectors, ids.flatten(), hiddens)
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vectors = vectors.reshape((vectors.shape[0], model.nO, model.nP))
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vectors += model.b
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vectors = model.ops.asarray(vectors)
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if model.nP >= 2:
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return model.ops.maxout(vectors)[0]
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else:
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return vectors * (vectors >= 0)
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tol_var = 0.01
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tol_mean = 0.01
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t_max = 10
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t_i = 0
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for t_i in range(t_max):
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acts1 = predict(ids, tokvecs)
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var = model.ops.xp.var(acts1)
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mean = model.ops.xp.mean(acts1)
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if abs(var - 1.0) >= tol_var:
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model.W /= model.ops.xp.sqrt(var)
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elif abs(mean) >= tol_mean:
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model.b -= mean
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else:
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break
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def link_vectors_to_models(vocab):
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vectors = vocab.vectors
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if vectors.name is None:
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vectors.name = VECTORS_KEY
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if vectors.data.size != 0:
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print(
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"Warning: Unnamed vectors -- this won't allow multiple vectors "
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"models to be loaded. (Shape: (%d, %d))" % vectors.data.shape
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)
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ops = Model.ops
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for word in vocab:
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if word.orth in vectors.key2row:
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word.rank = vectors.key2row[word.orth]
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else:
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word.rank = 0
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data = ops.asarray(vectors.data)
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# Set an entry here, so that vectors are accessed by StaticVectors
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# (unideal, I know)
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key = (ops.device, vectors.name)
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if key in thinc.extra.load_nlp.VECTORS:
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if thinc.extra.load_nlp.VECTORS[key].shape != data.shape:
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# This is a hack to avoid the problem in #3853. Maybe we should
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# print a warning as well?
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old_name = vectors.name
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new_name = vectors.name + "_%d" % data.shape[0]
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user_warning(Warnings.W019.format(old=old_name, new=new_name))
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vectors.name = new_name
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key = (ops.device, vectors.name)
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thinc.extra.load_nlp.VECTORS[key] = data
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def PyTorchBiLSTM(nO, nI, depth, dropout=0.2):
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if depth == 0:
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return layerize(noop())
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model = torch.nn.LSTM(nI, nO // 2, depth, bidirectional=True, dropout=dropout)
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return with_square_sequences(PyTorchWrapperRNN(model))
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def Tok2Vec(width, embed_size, **kwargs):
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pretrained_vectors = kwargs.get("pretrained_vectors", None)
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cnn_maxout_pieces = kwargs.get("cnn_maxout_pieces", 3)
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subword_features = kwargs.get("subword_features", True)
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conv_depth = kwargs.get("conv_depth", 4)
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bilstm_depth = kwargs.get("bilstm_depth", 0)
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cols = [ID, NORM, PREFIX, SUFFIX, SHAPE, ORTH]
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with Model.define_operators(
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{">>": chain, "|": concatenate, "**": clone, "+": add, "*": reapply}
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):
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norm = HashEmbed(width, embed_size, column=cols.index(NORM), name="embed_norm")
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if subword_features:
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prefix = HashEmbed(
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width, embed_size // 2, column=cols.index(PREFIX), name="embed_prefix"
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)
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suffix = HashEmbed(
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width, embed_size // 2, column=cols.index(SUFFIX), name="embed_suffix"
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)
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shape = HashEmbed(
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width, embed_size // 2, column=cols.index(SHAPE), name="embed_shape"
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)
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else:
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prefix, suffix, shape = (None, None, None)
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if pretrained_vectors is not None:
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glove = StaticVectors(pretrained_vectors, width, column=cols.index(ID))
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if subword_features:
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embed = uniqued(
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(glove | norm | prefix | suffix | shape)
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>> LN(Maxout(width, width * 5, pieces=3)),
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column=cols.index(ORTH),
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)
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else:
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embed = uniqued(
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(glove | norm) >> LN(Maxout(width, width * 2, pieces=3)),
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column=cols.index(ORTH),
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)
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elif subword_features:
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embed = uniqued(
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(norm | prefix | suffix | shape)
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>> LN(Maxout(width, width * 4, pieces=3)),
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column=cols.index(ORTH),
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)
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else:
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embed = norm
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convolution = Residual(
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ExtractWindow(nW=1)
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>> LN(Maxout(width, width * 3, pieces=cnn_maxout_pieces))
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)
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tok2vec = FeatureExtracter(cols) >> with_flatten(
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embed >> convolution ** conv_depth, pad=conv_depth
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)
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if bilstm_depth >= 1:
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tok2vec = tok2vec >> PyTorchBiLSTM(width, width, bilstm_depth)
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# Work around thinc API limitations :(. TODO: Revise in Thinc 7
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tok2vec.nO = width
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tok2vec.embed = embed
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return tok2vec
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def reapply(layer, n_times):
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def reapply_fwd(X, drop=0.0):
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backprops = []
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for i in range(n_times):
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Y, backprop = layer.begin_update(X, drop=drop)
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X = Y
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backprops.append(backprop)
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def reapply_bwd(dY, sgd=None):
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dX = None
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for backprop in reversed(backprops):
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dY = backprop(dY, sgd=sgd)
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if dX is None:
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dX = dY
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else:
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dX += dY
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return dX
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return Y, reapply_bwd
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return wrap(reapply_fwd, layer)
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def asarray(ops, dtype):
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def forward(X, drop=0.0):
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return ops.asarray(X, dtype=dtype), None
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return layerize(forward)
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def _divide_array(X, size):
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parts = []
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index = 0
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while index < len(X):
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parts.append(X[index : index + size])
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index += size
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return parts
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def get_col(idx):
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if idx < 0:
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raise IndexError(Errors.E066.format(value=idx))
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def forward(X, drop=0.0):
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if isinstance(X, numpy.ndarray):
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ops = NumpyOps()
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else:
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ops = CupyOps()
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output = ops.xp.ascontiguousarray(X[:, idx], dtype=X.dtype)
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def backward(y, sgd=None):
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dX = ops.allocate(X.shape)
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dX[:, idx] += y
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return dX
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return output, backward
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return layerize(forward)
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def doc2feats(cols=None):
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if cols is None:
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cols = [ID, NORM, PREFIX, SUFFIX, SHAPE, ORTH]
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def forward(docs, drop=0.0):
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feats = []
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for doc in docs:
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feats.append(doc.to_array(cols))
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return feats, None
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model = layerize(forward)
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model.cols = cols
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return model
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def print_shape(prefix):
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def forward(X, drop=0.0):
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return X, lambda dX, **kwargs: dX
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return layerize(forward)
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@layerize
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def get_token_vectors(tokens_attrs_vectors, drop=0.0):
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tokens, attrs, vectors = tokens_attrs_vectors
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def backward(d_output, sgd=None):
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return (tokens, d_output)
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return vectors, backward
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@layerize
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|
def logistic(X, drop=0.0):
|
|
xp = get_array_module(X)
|
|
if not isinstance(X, xp.ndarray):
|
|
X = xp.asarray(X)
|
|
# Clip to range (-10, 10)
|
|
X = xp.minimum(X, 10.0, X)
|
|
X = xp.maximum(X, -10.0, X)
|
|
Y = 1.0 / (1.0 + xp.exp(-X))
|
|
|
|
def logistic_bwd(dY, sgd=None):
|
|
dX = dY * (Y * (1 - Y))
|
|
return dX
|
|
|
|
return Y, logistic_bwd
|
|
|
|
|
|
def zero_init(model):
|
|
def _zero_init_impl(self, X, y):
|
|
self.W.fill(0)
|
|
|
|
model.on_data_hooks.append(_zero_init_impl)
|
|
return model
|
|
|
|
|
|
def getitem(i):
|
|
def getitem_fwd(X, drop=0.0):
|
|
return X[i], None
|
|
|
|
return layerize(getitem_fwd)
|
|
|
|
|
|
def build_tagger_model(nr_class, **cfg):
|
|
embed_size = util.env_opt("embed_size", 2000)
|
|
if "token_vector_width" in cfg:
|
|
token_vector_width = cfg["token_vector_width"]
|
|
else:
|
|
token_vector_width = util.env_opt("token_vector_width", 96)
|
|
pretrained_vectors = cfg.get("pretrained_vectors")
|
|
subword_features = cfg.get("subword_features", True)
|
|
with Model.define_operators({">>": chain, "+": add}):
|
|
if "tok2vec" in cfg:
|
|
tok2vec = cfg["tok2vec"]
|
|
else:
|
|
tok2vec = Tok2Vec(
|
|
token_vector_width,
|
|
embed_size,
|
|
subword_features=subword_features,
|
|
pretrained_vectors=pretrained_vectors,
|
|
)
|
|
softmax = with_flatten(Softmax(nr_class, token_vector_width))
|
|
model = tok2vec >> softmax
|
|
model.nI = None
|
|
model.tok2vec = tok2vec
|
|
model.softmax = softmax
|
|
return model
|
|
|
|
|
|
@layerize
|
|
def SpacyVectors(docs, drop=0.0):
|
|
batch = []
|
|
for doc in docs:
|
|
indices = numpy.zeros((len(doc),), dtype="i")
|
|
for i, word in enumerate(doc):
|
|
if word.orth in doc.vocab.vectors.key2row:
|
|
indices[i] = doc.vocab.vectors.key2row[word.orth]
|
|
else:
|
|
indices[i] = 0
|
|
vectors = doc.vocab.vectors.data[indices]
|
|
batch.append(vectors)
|
|
return batch, None
|
|
|
|
|
|
def build_text_classifier(nr_class, width=64, **cfg):
|
|
depth = cfg.get("depth", 2)
|
|
nr_vector = cfg.get("nr_vector", 5000)
|
|
pretrained_dims = cfg.get("pretrained_dims", 0)
|
|
with Model.define_operators({">>": chain, "+": add, "|": concatenate, "**": clone}):
|
|
if cfg.get("low_data") and pretrained_dims:
|
|
model = (
|
|
SpacyVectors
|
|
>> flatten_add_lengths
|
|
>> with_getitem(0, Affine(width, pretrained_dims))
|
|
>> ParametricAttention(width)
|
|
>> Pooling(sum_pool)
|
|
>> Residual(ReLu(width, width)) ** 2
|
|
>> zero_init(Affine(nr_class, width, drop_factor=0.0))
|
|
>> logistic
|
|
)
|
|
return model
|
|
|
|
lower = HashEmbed(width, nr_vector, column=1)
|
|
prefix = HashEmbed(width // 2, nr_vector, column=2)
|
|
suffix = HashEmbed(width // 2, nr_vector, column=3)
|
|
shape = HashEmbed(width // 2, nr_vector, column=4)
|
|
|
|
trained_vectors = FeatureExtracter(
|
|
[ORTH, LOWER, PREFIX, SUFFIX, SHAPE, ID]
|
|
) >> with_flatten(
|
|
uniqued(
|
|
(lower | prefix | suffix | shape)
|
|
>> LN(Maxout(width, width + (width // 2) * 3)),
|
|
column=0,
|
|
)
|
|
)
|
|
|
|
if pretrained_dims:
|
|
static_vectors = SpacyVectors >> with_flatten(
|
|
Affine(width, pretrained_dims)
|
|
)
|
|
# TODO Make concatenate support lists
|
|
vectors = concatenate_lists(trained_vectors, static_vectors)
|
|
vectors_width = width * 2
|
|
else:
|
|
vectors = trained_vectors
|
|
vectors_width = width
|
|
static_vectors = None
|
|
tok2vec = vectors >> with_flatten(
|
|
LN(Maxout(width, vectors_width))
|
|
>> Residual((ExtractWindow(nW=1) >> LN(Maxout(width, width * 3)))) ** depth,
|
|
pad=depth,
|
|
)
|
|
cnn_model = (
|
|
tok2vec
|
|
>> flatten_add_lengths
|
|
>> ParametricAttention(width)
|
|
>> Pooling(sum_pool)
|
|
>> Residual(zero_init(Maxout(width, width)))
|
|
>> zero_init(Affine(nr_class, width, drop_factor=0.0))
|
|
)
|
|
|
|
linear_model = build_bow_text_classifier(
|
|
nr_class, ngram_size=cfg.get("ngram_size", 1), exclusive_classes=False
|
|
)
|
|
if cfg.get("exclusive_classes"):
|
|
output_layer = Softmax(nr_class, nr_class * 2)
|
|
else:
|
|
output_layer = (
|
|
zero_init(Affine(nr_class, nr_class * 2, drop_factor=0.0)) >> logistic
|
|
)
|
|
model = (linear_model | cnn_model) >> output_layer
|
|
model.tok2vec = chain(tok2vec, flatten)
|
|
model.nO = nr_class
|
|
model.lsuv = False
|
|
return model
|
|
|
|
|
|
def build_bow_text_classifier(
|
|
nr_class, ngram_size=1, exclusive_classes=False, no_output_layer=False, **cfg
|
|
):
|
|
with Model.define_operators({">>": chain}):
|
|
model = with_cpu(
|
|
Model.ops, extract_ngrams(ngram_size, attr=ORTH) >> LinearModel(nr_class)
|
|
)
|
|
if not no_output_layer:
|
|
model = model >> (cpu_softmax if exclusive_classes else logistic)
|
|
model.nO = nr_class
|
|
return model
|
|
|
|
|
|
@layerize
|
|
def cpu_softmax(X, drop=0.0):
|
|
ops = NumpyOps()
|
|
|
|
def cpu_softmax_backward(dY, sgd=None):
|
|
return dY
|
|
|
|
return ops.softmax(X), cpu_softmax_backward
|
|
|
|
|
|
def build_simple_cnn_text_classifier(tok2vec, nr_class, exclusive_classes=False, **cfg):
|
|
"""
|
|
Build a simple CNN text classifier, given a token-to-vector model as inputs.
|
|
If exclusive_classes=True, a softmax non-linearity is applied, so that the
|
|
outputs sum to 1. If exclusive_classes=False, a logistic non-linearity
|
|
is applied instead, so that outputs are in the range [0, 1].
|
|
"""
|
|
with Model.define_operators({">>": chain}):
|
|
if exclusive_classes:
|
|
output_layer = Softmax(nr_class, tok2vec.nO)
|
|
else:
|
|
output_layer = (
|
|
zero_init(Affine(nr_class, tok2vec.nO, drop_factor=0.0)) >> logistic
|
|
)
|
|
model = tok2vec >> flatten_add_lengths >> Pooling(mean_pool) >> output_layer
|
|
model.tok2vec = chain(tok2vec, flatten)
|
|
model.nO = nr_class
|
|
return model
|
|
|
|
|
|
def build_nel_encoder(embed_width, hidden_width, ner_types, **cfg):
|
|
if "entity_width" not in cfg:
|
|
raise ValueError(Errors.E144.format(param="entity_width"))
|
|
|
|
conv_depth = cfg.get("conv_depth", 2)
|
|
cnn_maxout_pieces = cfg.get("cnn_maxout_pieces", 3)
|
|
pretrained_vectors = cfg.get("pretrained_vectors", None)
|
|
context_width = cfg.get("entity_width")
|
|
|
|
with Model.define_operators({">>": chain, "**": clone}):
|
|
# context encoder
|
|
tok2vec = Tok2Vec(
|
|
width=hidden_width,
|
|
embed_size=embed_width,
|
|
pretrained_vectors=pretrained_vectors,
|
|
cnn_maxout_pieces=cnn_maxout_pieces,
|
|
subword_features=True,
|
|
conv_depth=conv_depth,
|
|
bilstm_depth=0,
|
|
)
|
|
|
|
model = (
|
|
tok2vec
|
|
>> flatten_add_lengths
|
|
>> Pooling(mean_pool)
|
|
>> Residual(zero_init(Maxout(hidden_width, hidden_width)))
|
|
>> zero_init(Affine(context_width, hidden_width, drop_factor=0.0))
|
|
)
|
|
|
|
model.tok2vec = tok2vec
|
|
model.nO = context_width
|
|
return model
|
|
|
|
|
|
@layerize
|
|
def flatten(seqs, drop=0.0):
|
|
ops = Model.ops
|
|
lengths = ops.asarray([len(seq) for seq in seqs], dtype="i")
|
|
|
|
def finish_update(d_X, sgd=None):
|
|
return ops.unflatten(d_X, lengths, pad=0)
|
|
|
|
X = ops.flatten(seqs, pad=0)
|
|
return X, finish_update
|
|
|
|
|
|
def concatenate_lists(*layers, **kwargs): # pragma: no cover
|
|
"""Compose two or more models `f`, `g`, etc, such that their outputs are
|
|
concatenated, i.e. `concatenate(f, g)(x)` computes `hstack(f(x), g(x))`
|
|
"""
|
|
if not layers:
|
|
return noop()
|
|
drop_factor = kwargs.get("drop_factor", 1.0)
|
|
ops = layers[0].ops
|
|
layers = [chain(layer, flatten) for layer in layers]
|
|
concat = concatenate(*layers)
|
|
|
|
def concatenate_lists_fwd(Xs, drop=0.0):
|
|
drop *= drop_factor
|
|
lengths = ops.asarray([len(X) for X in Xs], dtype="i")
|
|
flat_y, bp_flat_y = concat.begin_update(Xs, drop=drop)
|
|
ys = ops.unflatten(flat_y, lengths)
|
|
|
|
def concatenate_lists_bwd(d_ys, sgd=None):
|
|
return bp_flat_y(ops.flatten(d_ys), sgd=sgd)
|
|
|
|
return ys, concatenate_lists_bwd
|
|
|
|
model = wrap(concatenate_lists_fwd, concat)
|
|
return model
|
|
|
|
|
|
def masked_language_model(vocab, model, mask_prob=0.15):
|
|
"""Convert a model into a BERT-style masked language model"""
|
|
|
|
random_words = _RandomWords(vocab)
|
|
|
|
def mlm_forward(docs, drop=0.0):
|
|
mask, docs = _apply_mask(docs, random_words, mask_prob=mask_prob)
|
|
mask = model.ops.asarray(mask).reshape((mask.shape[0], 1))
|
|
output, backprop = model.begin_update(docs, drop=drop)
|
|
|
|
def mlm_backward(d_output, sgd=None):
|
|
d_output *= 1 - mask
|
|
return backprop(d_output, sgd=sgd)
|
|
|
|
return output, mlm_backward
|
|
|
|
return wrap(mlm_forward, model)
|
|
|
|
|
|
class _RandomWords(object):
|
|
def __init__(self, vocab):
|
|
self.words = [lex.text for lex in vocab if lex.prob != 0.0]
|
|
self.probs = [lex.prob for lex in vocab if lex.prob != 0.0]
|
|
self.words = self.words[:10000]
|
|
self.probs = self.probs[:10000]
|
|
self.probs = numpy.exp(numpy.array(self.probs, dtype="f"))
|
|
self.probs /= self.probs.sum()
|
|
self._cache = []
|
|
|
|
def next(self):
|
|
if not self._cache:
|
|
self._cache.extend(
|
|
numpy.random.choice(len(self.words), 10000, p=self.probs)
|
|
)
|
|
index = self._cache.pop()
|
|
return self.words[index]
|
|
|
|
|
|
def _apply_mask(docs, random_words, mask_prob=0.15):
|
|
# This needs to be here to avoid circular imports
|
|
from .tokens.doc import Doc
|
|
|
|
N = sum(len(doc) for doc in docs)
|
|
mask = numpy.random.uniform(0.0, 1.0, (N,))
|
|
mask = mask >= mask_prob
|
|
i = 0
|
|
masked_docs = []
|
|
for doc in docs:
|
|
words = []
|
|
for token in doc:
|
|
if not mask[i]:
|
|
word = _replace_word(token.text, random_words)
|
|
else:
|
|
word = token.text
|
|
words.append(word)
|
|
i += 1
|
|
spaces = [bool(w.whitespace_) for w in doc]
|
|
# NB: If you change this implementation to instead modify
|
|
# the docs in place, take care that the IDs reflect the original
|
|
# words. Currently we use the original docs to make the vectors
|
|
# for the target, so we don't lose the original tokens. But if
|
|
# you modified the docs in place here, you would.
|
|
masked_docs.append(Doc(doc.vocab, words=words, spaces=spaces))
|
|
return mask, masked_docs
|
|
|
|
|
|
def _replace_word(word, random_words, mask="[MASK]"):
|
|
roll = numpy.random.random()
|
|
if roll < 0.8:
|
|
return mask
|
|
elif roll < 0.9:
|
|
return random_words.next()
|
|
else:
|
|
return word
|
|
|
|
|
|
def get_cossim_loss(yh, y):
|
|
# Add a small constant to avoid 0 vectors
|
|
yh = yh + 1e-8
|
|
y = y + 1e-8
|
|
# https://math.stackexchange.com/questions/1923613/partial-derivative-of-cosine-similarity
|
|
xp = get_array_module(yh)
|
|
norm_yh = xp.linalg.norm(yh, axis=1, keepdims=True)
|
|
norm_y = xp.linalg.norm(y, axis=1, keepdims=True)
|
|
mul_norms = norm_yh * norm_y
|
|
cosine = (yh * y).sum(axis=1, keepdims=True) / mul_norms
|
|
d_yh = (y / mul_norms) - (cosine * (yh / norm_yh ** 2))
|
|
loss = xp.abs(cosine - 1).sum()
|
|
return loss, -d_yh
|