seq2feature_ngram {ProcData}

ngram feature extraction

Description

seq2feature_ngram extracts ngram features from response processes.

Usage

seq2feature_ngram(seqs, level = 2, type = "binary", sep = "\t")

Arguments

seqs

an object of class "proc"

level

an integer specifying the max length of ngrams

type

a character string ("binary", "freq", or "weighted") specifying the type of ngram features.

sep

action seperator within ngram.

Details

Three types of ngram features can be extracted. type = "binary" gives binary ngram features indicating whether an ngram appears in a response process. type = "freq" gives ngram frequency features. Each feature is the count of the corresponding ngram in a response process. type = "weighted" gives the weighted ngram features proposed in He and von Davier (2015).

Value

a matrix of ngram features

References

He Q., von Davier M. (2015). Identifying Feature Sequences from Process Data in Problem-Solving Items with N-Grams. In: van der Ark L., Bolt D., Wang WC., Douglas J., Chow SM. (eds) Quantitative Psychology Research. Springer Proceedings in Mathematics & Statistics, vol 140. Springer, Cham.

See Also

Other feature extraction methods: aseq2feature_seq2seq, atseq2feature_seq2seq, seq2feature_mds_large, seq2feature_mds, seq2feature_seq2seq, tseq2feature_seq2seq

Examples

seqs <- seq_gen(100)
theta <- seq2feature_ngram(seqs)