Count how many times each string from a column appear (no exact match) in another column in R

Question

My data looks like this

df <- data.frame(id = c("p3", "p5", "p8", "p9", "p10", "p11"), pedi = c("p1/p2", "p3/p4", "p3/p5", "(p3/p4)/p5", "p5/p8", "p4/p10"))

I am trying this

id <- df$id 
for (i in length(id)) {
  df$id_in_pedi <- sum(grepl(i, df$pedi))
}

But it does not work. The result I am looking for is this:

df <- data.frame(id = c("p3", "p5", "p8", "p9", "p10", "p11"),
                 pedi = c("p1/p2", "p3/p4", "p3/p5", "(p3/p4)/p5", "p5/p8", "p4/p10"),
                 id_in_pedi = c(3,3,1,0,1,0))

Thanks

Answer 1

In tidyverse:

library(tidyverse)
df %>%
   mutate(id_in_pedi = str_count(toString(pedi), id))

   id       pedi id_in_pedi
1  p3      p1/p2          3
2  p5      p3/p4          3
3  p8      p3/p5          1
4  p9 (p3/p4)/p5          0
5 p10      p5/p8          1
6 p11     p4/p10          0

in Base R: Using sapply:

transform(df, id_in_pedi = colSums(sapply(id, grepl, pedi, USE.NAMES = FALSE)))

   id       pedi id_in_pedi
1  p3      p1/p2          3
2  p5      p3/p4          3
3  p8      p3/p5          1
4  p9 (p3/p4)/p5          0
5 p10      p5/p8          1
6 p11     p4/p10          0

Using Vectorize:

colSums(Vectorize(grepl)(df$id, list(df$pedi)))
 p3  p5  p8  p9 p10 p11 
  3   3   1   0   1   0