1. R語言運行效率分析(5)

方法5： 採用 which 語句

1: 自定義函數

# digital was translated into englishname
Month_name_which<-function(month){
  Month_name<-month
  Month_name[(which(Month_name==1))]<-"Jan"
  Month_name[(which(Month_name==2))]<-"Feb"
  Month_name[(which(Month_name==3))]<-"Mar"
  Month_name[(which(Month_name==4))]<-"Apr"
  Month_name[(which(Month_name==5))]<-"May"
  Month_name[(which(Month_name==6))]<-"Jun"
  Month_name[(which(Month_name==7))]<-"Jul"
  Month_name[(which(Month_name==8))]<-"Aug"
  Month_name[(which(Month_name==9))]<-"Sep"
  Month_name[(which(Month_name==10))]<-"Oct"
  Month_name[(which(Month_name==11))]<-"Nov"
  Month_name[(which(Month_name==12))]<-"Dec"
  
  return(Month_name)
}
Season_name_which<-function(month){
  Season_name<-month
  Season_name[which(Season_name %in% c(12,1,2))]<-"Winter"
  Season_name[which(Season_name %in% c(3,4,5))]<-"Spring"
  Season_name[which(Season_name %in% c(6,7,8))]<-"Summer"
  Season_name[which(Season_name %in% c(9,10,11))]<-"Autumn"
 
  return(Season_name)
}
result_which<-function(month){
  Month_name_which<-Month_name_which(month)# months' names
  Season_name_whichh<-Season_name_which(month) #seasons' names
  df<-data.frame(month,Month_name_which,Season_name_whichh)
  return(df)
}

2: 調用函數進行運算

month<-month_digital(10)
microbenchmark(Month_name_which(month))
microbenchmark(Season_name_which(month))
microbenchmark(result_which(month))

Unit: microseconds
                    expr    min      lq     mean median      uq      max neval
 Month_name_which(month) 71.668 73.2195 393.5091 74.426 76.0145 31879.35   100
Unit: microseconds
                     expr    min      lq     mean median     uq      max neval
 Season_name_which(month) 42.812 43.9625 157.1115 44.655 45.477 11199.92   100
Unit: microseconds
                expr    min       lq     mean  median       uq      max neval
 result_which(month) 771.61 786.8795 886.8605 800.243 829.8675 4943.644   100

(未完！待續……)