keras: skipgrams – R documentation

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keras

skipgrams

Generates skipgram word pairs.

Description

Generates skipgram word pairs.

Usage

skipgrams(
  sequence,
  vocabulary_size,
  window_size = 4,
  negative_samples = 1,
  shuffle = TRUE,
  categorical = FALSE,
  sampling_table = NULL,
  seed = NULL
)

Arguments

`sequence`	A word sequence (sentence), encoded as a list of word indices (integers). If using a `sampling_table`, word indices are expected to match the rank of the words in a reference dataset (e.g. 10 would encode the 10-th most frequently occuring token). Note that index 0 is expected to be a non-word and will be skipped.
`vocabulary_size`	Int, maximum possible word index + 1
`window_size`	Int, size of sampling windows (technically half-window). The window of a word `w_i` will be `[i-window_size, i+window_size+1]`
`negative_samples`	float >= 0. 0 for no negative (i.e. random) samples. 1 for same number as positive samples.
`shuffle`	whether to shuffle the word couples before returning them.
`categorical`	bool. if `FALSE`, labels will be integers (eg. `[0, 1, 1 .. ]`), if `TRUE` labels will be categorical eg. `[[1,0],[0,1],[0,1] .. ]`
`sampling_table`	1D array of size `vocabulary_size` where the entry i encodes the probabibily to sample a word of rank i.
`seed`	Random seed

Details

This function transforms a list of word indexes (lists of integers) into lists of words of the form:

(word, word in the same window), with label 1 (positive samples).
(word, random word from the vocabulary), with label 0 (negative samples).

Read more about Skipgram in this gnomic paper by Mikolov et al.: Efficient Estimation of Word Representations in Vector Space

Value

List of couples, labels where:

couples is a list of 2-element integer vectors: [word_index, other_word_index].
labels is an integer vector of 0 and 1, where 1 indicates that other_word_index was found in the same window as word_index, and 0 indicates that other_word_index was random.
if categorical is set to TRUE, the labels are categorical, ie. 1 becomes [0,1], and 0 becomes [1, 0].