x <- c("09-01-01", "09-01-02", "09-01-03")
parse_date(x, c("%y", "%m", "%d"), seps = "-")
# "2009-01-01 UTC" "2009-01-02 UTC" "2009-01-03 UTC"
ymd(x)
# "2009-01-01 UTC" "2009-01-02 UTC" "2009-01-03 UTC"
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