library(forecast)
amtrak.data <- read.csv("/Users/shalaw/Downloads/Amtrak data.csv")
ridership.ts <- ts(amtrak.data$Ridership, start = c(1991, 1), end = c(2004, 3), freq = 12)
stepsAhead <- 36
nTrain<-length(ridership.ts)- stepsAhead
train.ts<-window(ridership.ts,start = c(1991,1),end = c(1991, nTrain))