stringr VS glue

Perhaps str_extract_all() from stringr? (since you're already using dplyr)

There are base R ways of finding strings grep(), as well as packages such as {stringer} (cheat sheet available here: https://stringr.tidyverse.org/)

If you're unfamiliar with regex, it may help you review the stringr cheat sheet: https://stringr.tidyverse.org/

Without knowing more, it seems likely that some combination of stringr and fuzzyjoin will be what you need.

Search for info about the grepl-function and read the cheat sheet from the stringr-package, that should get you started: https://stringr.tidyverse.org/

Looks like you have a misunderstanding about the right-most column. Don't think of the cell values as vectors of length=N elements, c("gene1", "gene2", ..."geneN"). Instead, think of each cell as a character string (vector of length=1), "gene 1, gene 2, ... geneN". Finding specific sequence of characters within a string is different from finding matching elements of vectors. Without changing the column, you can use regular expressions and base R string functions and/or stringr if you're more comfortable with tidyverse.

This. I would also suggest looking at glue. It is overkill for something simple like this, but it helps a lot for a larger text with multiple information from code.