# Ordering vectors Simplified implementation of `order`. For large vectors, typically is about 3x faster for numbers and 20x faster for characters. ```r order2(x) ``` ## Arguments - `x`: a vector of class numeric, integer, character, factor, or logical. Long vectors are not supported. ## Examples ```r chars<-as.character(sample(1e3,1e4,TRUE)) system.time(a<-order(chars)) system.time(b<-order2(chars)) identical(chars[a],chars[b]) ints<-as.integer(sample(1e3,1e4,TRUE)) system.time(a<-order(ints)) system.time(b<-order2(ints)) identical(ints[a],ints[b]) nums<-runif(1e4) system.time(a<-order(nums)) system.time(b<-order2(nums)) identical(nums[a],nums[b]) logs<-as.logical(sample(0:1,1e6,TRUE)) system.time(a<-order(logs)) system.time(b<-order2(logs)) identical(logs[a],logs[b]) facts<-as.factor(as.character(sample(1e3,1e4,TRUE))) system.time(a<-order(facts)) system.time(b<-order2(facts)) identical(facts[a],facts[b]) #How are special values like NA and Inf handled? #For numerics, values sort intuitively, with the important note that NA and #NaN will come after all real numbers but before Inf. (function (x) x[order2(x)])(c(1,2,NA,NaN,Inf,-Inf)) #For characters, values sort correctly with NA at the end. (function (x) x[order2(x)])(c('C','B',NA,'A')) #For factors, values sort correctly with NA at the end. (function (x) x[order2(x)])(as.factor(c('C','B',NA,'A'))) #Ordering a data frame using order2 df<-data.frame(one=as.character(1:4e5), two=sample(1:1e5,4e5,TRUE), three=sample(letters,4e5,TRUE),stringsAsFactors=FALSE) system.time(a<-df[order(df$one),]) system.time(b<-df[order2(df$one),]) system.time(a<-df[order(df$two),]) system.time(b<-df[order2(df$two),]) ## Not run: chars<-as.character(sample(1e5,1e6,TRUE)) system.time(a<-order(chars)) system.time(b<-order2(chars)) ints<-as.integer(sample(1e5,1e6,TRUE)) system.time(result<-order(ints)) system.time(result<-order2(ints)) nums<-runif(1e6) system.time(result<-order(nums)) system.time(result<-order2(nums)) logs<-as.logical(sample(0:1,1e7,TRUE)) system.time(result<-order(logs)) system.time(result<-order2(logs)) facts<-as.factor(as.character(sample(1e5,1e6,TRUE))) system.time(a<-order(facts)) system.time(b<-order2(facts)) identical(facts[a],facts[b]) ## End(Not run) ```

order2 function