You could merge your table of conditions to the original dataset and filter them conditionally. Consider a1 and a2 like your sp and day values, and obs to be like your ar value.
library(data.table)
dataset <- data.table(
a1 = c("A","B","C","B","A","A","A","A"),
a2 = c("P","Q","Q","Q","R","R","P","Q"),
obs = c(3,2,3,4,2,4,8,0)
)
constraints <- data.table(
a1 = c("A","B","C","A","B","C","A","B","C"),
a2 = c("P","P","P","Q","Q","Q","R","R","R"),
lower = c(1,2,3,4,3,2,3,2,5),
upper = c(6,4,5,7,5,6,5,3,7)
)
checkingdataset <- merge(dataset,constraints, by = c("a1","a2"), all.x = TRUE)
checkingdataset[obs <= upper & obs >= lower, obs.keep := TRUE]
# a1 a2 obs lower upper obs.keep
#1: A P 3 1 6 TRUE
#2: A P 8 1 6 NA
#3: A Q 0 4 7 NA
#4: A R 2 3 5 NA
#5: A R 4 3 5 TRUE
#6: B Q 2 3 5 NA
#7: B Q 4 3 5 TRUE
#8: C Q 3 2 6 TRUE