Here is an example, for context...
df %>% filter(str_detect(col, "(?i)animal"))
And another one:
df1 <- df %>% filter(str_detect(col, "(?i)^([a-z]).*\\1$"))
Here is an example, for context...
df %>% filter(str_detect(col, "(?i)animal"))
And another one:
df1 <- df %>% filter(str_detect(col, "(?i)^([a-z]).*\\1$"))