library(lubridate)
date1 <- as.POSIXct("2017-03-31 14:32:00")
date2 <- as.POSIXct("2017-03-31 14:33:00")
int <- new_interval(date1, date2)
df[df$datetime %within% int,]
用lubridate包可以轻松实现,
参考http://stackoverflow.com/questions/19420155/subset-rows-according-to-a-range-of-time