library(openxlsx)
excel_sample1<-read.xlsx("http://kanggc.iptime.org/book/data/sample1-n.xlsx")
excel_sample1
excel_sample1_dat<- data.matrix(excel_sample1)
excel_sample1_dat
year<-excel_sample1_dat[,1]
gdp<-excel_sample1_dat[,2]
consumption<-excel_sample1_dat[,3]
summary(excel_sample1_dat)