Generates skipgram word pairs.

Generates skipgram word pairs.

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] .. ]

[[1,0]: R:[1,0 [0,1]: R:0,1 [0,1]: R: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

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].

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

See also

Other text preprocessing: make_sampling_table, pad_sequences, text_hashing_trick, text_one_hot, text_to_word_sequence