1請重新設計動物園程式，使用sample()函數，在10和100間，自行產生30天動物出現次數
ch15_1 <- function( )
{
an_info <-
matrix(sample(10:100, 90, replace = T), ncol = 3)
colnames(an_info) <-
c("Tiger", "Lion", "Leopard")
rownames(an_info) <-
c(paste(rep("Day", times = 30), 1:30))
print(an_info)
apply(an_info, 2,
function(x) c(max(x), min(x), round(mean(x))))
}
2.設計一個比大小的程式，先行設定電腦贏的機率
ch15_2 <- function( )
{
cat("請輸入1~10內之數值資料，若想結束，請按Enter")
x1 <- scan()
x2 <- sample(1:10, 1,
replace = T,c(1 ,2 , 3, 4, 5, 6, 7, 8, 9, 10))
x3 <- "abc"
if(x1 > x2)
{
x3 <-
"Win"
}else if (x1 == x2)
{
x3 <-
"Flat"
}else {
x3 <-
"Lose"
}
cat(x3)
}
3.設計骰子遊戲，每次結束詢問一次是否重玩
ch15_3 <- function( )
{
x2 <- y
repeat{
x1 <- sample(1:6, 3, replace = T)
cat("Dice game :", x1, "\n")
cat("Play again? y/n")
x2 <- scan(what = character())
if(x2 == "n") break
}
print("Game over")
}
4.請計算iris花瓣及花萼平均的length/width
ld.r.petal <- mean(iris$Petal.Length / iris$Petal.Width)
ld.r.sepal <- mean(iris$Sepal.Length / iris$Petal.Width)
ch15_4 <- cbind(ld.r.petal, ld.r.sepal)
5.請將islands物件—面積大小分成10等分
ch15_5 <- function( )
{
islands_2 <- as.data.frame(islands)
label.islands <- cut(islands, 10,
labels = c("Low", "9th", "8th", "7th",
"6th", "5th", "4th", "3rd", "2nd", "High"))
islands_new <- cbind(as.character(label.islands), islands_2)
dimnames(islands_new)[[2]] <- c("grade", "area")
x <- order(islands, decreasing = T)
y <- islands_new[x, ]
print(y)
}
6.合併state.x77中人口少於500萬盒月收少於500美元的州
ch15_6 <- function( )
{
mystate.x77 <- as.data.frame(state.x77)
mystate.x77$Name <- rownames(state.x77)
rownames(mystate.x77) <- NULL
mypopu.states <- mystate.x77[mystate.x77$Population < 5000, c("Name", "Population")]
myincome.states <- mystate.x77[mystate.x77$Income < 5000, c("Name", "Income")]
x <- merge(mypopu.states, myincome.states)
print(x)
}
7.承上題，只要其中一個條件符合即可
ch15_7 <- function( )
{
mystate.x77 <- as.data.frame(state.x77)
mystate.x77$Name <- rownames(state.x77)
rownames(mystate.x77) <- NULL
mypopu.states <- mystate.x77[mystate.x77$Population < 5000, c("Name", "Population")]
myincome.states <- mystate.x77[mystate.x77$Income < 5000, c("Name", "Income")]
x <- merge(mypopu.states, myincome.states, all = T)
print(x)
}
8.計算mtcars裡不同汽缸數車輛之平均馬力(hp)
ch15_8 <- function( )
{
mycar <- within(mtcars,
cyl <- factor(cyl, levels = c(4, 6, 8),
labels = c("四汽缸", "六汽缸", "八汽缸")))
x <- with(mycar, tapply(hp, cyl, mean))
print(x)
}
9.自行設5位球員主力，到各處比賽之資料，製作長格式及寬格式數據，同時建立樞紐分析表
ch15_9 <- function( )
{
game <- c(paste(rep("G",times = 10), 1:10, sep = ""))
site <- c("LA", "SF", "SF", "NYC", "LA", "TX", "TX", "SF", "NYC", "LA")
Lin <- c(sample(10:20, 10, replace = T, set.seed(1)))
Wang <- c(sample(10:25, 10, replace = T, set.seed(2)))
Lu <- c(sample(15:25, 10, replace = T, set.seed(3)))
Pete <- c(sample(9:18, 10, replace = T, set.seed(4)))
Jordan <- c(sample(16:28, 10, replace = T, set.seed(5)))
balls <- data.frame(game, site, Lin, Wang, Lu, Pete, Jordan)
lballs <- melt(balls, id.var = c("game", "site"),
variable.name = "name", value.name = "points")
site.ball <- dcast(lballs, site ~ name, sum)
game.site.ball <- dcast(lballs, game + site ~ name, sum)
cat("Enter a for short form; b for long form;
c for site~name; d for game + site ~ name")
x <- scan(what = character())
if(x == "a") print(balls)
else if(x == "b") print(lballs)
else if(x == "c") print(site.ball)
else if(x == "d") print(game.site.ball)
else print("Error")
}
