Remove words from rows in a dataframe

Question

I have a dataframe, with a lot of trigrams and their frequencies.

How can I add a third column (let's called it finalWord) where only the last word of the trigram is displayed?

Here is an example of the dataframe:

x <- data.frame(trigrams = c("I have to", "I need to"), freq = c(10, 7))

The output should be:

x <- data.frame(trigrams = c("I have to", "I need to"), freq = c(10, 7), finalWord = c("to", "to"))

Answer 1

We can use sub

x$finalword <- sub(".*\\s+", '', x$trigrams)
x$finalword
#[1] "to" "to"

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library(stringi)
stri_extract_last(x$trigrams, regex="\\w+")