I am confused on below result on pattern match using grepl() function -
grepl("[0-9]{2}-[0-9]{2}-[0-9]{2}", "2010-04-09") # TRUE
grepl("[0-9]{4}-[0-9]{2}-[0-9]{2}", "2010-04-09") #TRUE
Shouldn't I expect the first result to be FALSE?
Any pointer will be highly appreciated.
The result is correct.
grepl is looking for the pattern of xx-xx-xx, where x is a digit, and that does appear in the first query. If you want to query starting from the beginning of the string, you can use the ^ symbol.
For example, if you were to run grepl("^[0-9]{2}-[0-9]{2}-[0-9]{2}", "2010-04-09"), you'd get FALSE, but grepl("^[0-9]{4}-[0-9]{2}-[0-9]{2}", "2010-04-09") would return TRUE.
PS: On the opposite end, $ indicates the end of the string.