udpipe (version 0.8.3)

txt_previousgram: Based on a vector with a word sequence, get n-grams (looking backward)

Description

If you have annotated your text using udpipe_annotate, your text is tokenised in a sequence of words. Based on this vector of words in sequence getting n-grams comes down to looking at the previous word and the subsequent previous word andsoforth. These words can be pasted together to form an n-gram containing the second previous word, the previous word, the current word ...

Usage

txt_previousgram(x, n = 2, sep = " ")

Arguments

x

a character vector where each element is just 1 term or word

n

an integer indicating the ngram. Values of 1 will keep the x, a value of 2 will append the previous term to the current term, a value of 3 will append the second previous term term and the previous term preceding the current term to the current term

sep

a character element indicating how to paste the subsequent words together

Value

a character vector of the same length of x with the n-grams

See Also

paste, shift

Examples

# NOT RUN {
x <- sprintf("%s%s", LETTERS, 1:26)
txt_previousgram(x, n = 2)

data.frame(words = x,
           bigram = txt_previousgram(x, n = 2),
           trigram = txt_previousgram(x, n = 3, sep = "-"),
           quatrogram = txt_previousgram(x, n = 4, sep = ""),
           stringsAsFactors = FALSE)

x <- c("A1", "A2", "A3", NA, "A4", "A5")
data.frame(x, 
           bigram = txt_previousgram(x, n = 2, sep = "_"),
           stringsAsFactors = FALSE)
# }