Finding and replacing strings in cells of a matrix in R

Question

I'm trying to process a survey, in which one of the questions asks the respondents to name a friend. Now I have a matrix like this:

I want to save these results in a relational database. I have assigned every person a unique ID, and want the answers to be saved as a last of ID's. So that the table looks like this:

My code so far:

i've tried

df$name %in% df$friends

which did not give any results. I'm now trying to use a for loop with str_detect:

friends <- df$friends
names <- df$name
for (i in 1:length(names)) {
  friends_called <- str_detect(friends, names[i])
  id_index <- grep(names[i], df$name)
  id <- df$id[id_index]
  for (j in 1:length(friends_called)) {
    if(friends_called[j] == T) {
      df$friends_id[j] <- paste(df$friends_id[j], id, ",", sep="")
    }
df$friends <- df$friends_id

But I have some issues with it:

1. It's not working
2. It uses two loops, which i'm used to from writing python but I read that i should avoid them in R
3. The string matching needs to be fuzzy (If Anna wrote "Jon" instead of "John", it should still match.

Does anyone have suggestions on how to tackle this?

Answer 1

You can do this without a loop in tidyverse as follows:

df %>%
  mutate(friends = map(friends, ~ df %>% 
                         filter(str_detect(.x,name)) %>% 
                         select(id) %>% 
                         unlist() %>% 
                         paste(collapse = ',')))

gives

   id   name friends
1 a1d   John b2e,c3f
2 b2e   Anna     a1d
3 c3f Denise

or with base R you can use sapply:

df$friends <- sapply(friends, function(x) paste(id[str_detect(x,name)],collapse = ','))