r compare text in two columns by row

Question

I would like to compare text in column X1 with text in column X2 and Produce a list of words that appear in X1 but not X2, and vice versa. For example:

df <- data.frame("X1" = c("the fox ate grapes", "the cat ate"), "X2" = c("the fox ate watermelon", "the cat ate backwards"))

I'm trying to generate columns such as X3 - grapes watermelon X4 - backwards

The data frame has hundreds of rows, and the text in some cells in up to 50 words or so.

Answer 1

I dont understand how you want to organize the the output in X3 and X4 but maybe this helps:

words_x1 <- (df$X1 %>% paste(collapse = " ") %>% str_split(" "))[[1]] %>% unique()
words_x2 <- (df$X2 %>% paste(collapse = " ") %>% str_split(" "))[[1]] %>% unique()

c(words_x1[!(words_x1 %in% words_x2)], words_x2[!(words_x2 %in% words_x1)])

I think what you want to achieve is something like this (note that I am using a tibble as it does not seem to work with data.frame.

library(dplyr)
library(purrr)

df <- tibble(
  X1 = c("the fox ate grapes", "the cat ate"),
  X2 = c("the fox ate watermelon", "the cat ate backwards")
)
myfunction <- function(x1, x2) {
  w1 <- strsplit(x1, " ")[[1]]
  w2 <- strsplit(x2, " ")[[1]]
  c(w1[!(w1 %in% w2)], w2[!(w2 %in% w1)])
}

map2(df$X1, df$X2, myfunction)