Wildcards for filter function in dplyr

Question

I am using dplyr and I would like to filter my dataframe (biotypes) according to sample IDs which are the first column of the data frame, e.g. they look like this:

ID
chrX.tRNA494-SerAGA 
chrX.tRNA636-AlaCGC
mmu_piR_000007
...

I want to filter IDs starting with "chr" from IDs starting with "mmu":

biotype<- biotype %>% 
  filter( str_detect (biotype, "^chr") ==TRUE )
biotype

Can anyone help please? I am just looking for something like * that allows me to filter all rows that have a string starting with these particular characters ...

Answer 1

I think you were very close already.

library(stringr)
biotype %>% filter(str_detect(ID,"^chr"))

(you need to specify the column name, and == TRUE is superfluous).

Answer 2

What about grepl?

biotype <- biotype %>%
    filter(grepl('^chr', ID))