第2周书面作业

3.5

rm(list=ls());options(stringsAsFactors=F)
y <- c(2,4,3,2,4,7,7,2,2,5,4,5,6,8,5,10,7,12,12,6,6,7,11,6,6,7,9,5,5,10,6,3,10)
x <- factor(c(rep(1,11),rep(2,10),rep(3,12)))

用plot函数绘制箱线图

plot(x,y)

用boxplot函数绘制箱线图

boxplot(y~x)

从图中可以看出：菌型1与菌型2有显著差异，菌型2与菌型3无明显差异

3.7

dat <- data.frame(id=c(1:19),
                  name=c("Alice","Becka","Gail","Karen","Kathy","Mary","Sandy","Sharon","Tammy","Alfred","Duke","Guido","James","Jeffrey","John","Philip","Robert","Thomas","William"),
                  sex=rep(c("F","M"),c(9,10)),
                  age=c(13,13,14,12,12,15,11,15,14,14,14,15,12,13,12,16,12,11,15),
                  height=c(56.5,65.3,64.3,56.3,59.8,66.5,51.3,62.5,62.8,69.0,63.5,67.0,57.3,62.5,59.0,72.0,64.8,57.5,66.5),
                  weight=c(84.0,98.0,90.0,77.0,84.5,112.0,50.5,112.5,102.5,112.5,102.5,133.0,83.0,84.0,99.5,150.0,128.0,85.0,112.0))

(1)试绘出体重对于身高的散点图

plot(dat$height,dat$weight,main="weight~height")

(2)绘出不同性别情况下，体重与身高的散点图；

coplot(dat$height~dat$weight | dat$sex, xlab = c("weight", "Given : sex"),ylab="height")

(3)绘出不同年龄段的体重与身高的散点图；

coplot(dat$height~dat$weight | dat$age, xlab = c("weight", "Given : age"),ylab="height")

(4)给出不同性别和不同年龄段的体重与身高的散点图；

coplot(dat$height~dat$weight | dat$age+ dat$sex)

3.8

x <- seq(-2,3,0.05)
y <- seq(-1,7,0.05)
f <- function(x,y) x^4-2*x^2*y+x^2-2*x*y+2*y^2+4.5*x-4*y+4
z <- outer(x,y,f)
#三维网格曲面
persp(x,y,z,theta=70,phi=20,expand=0.7,col="lightblue")

#二维等值线
contour(x,y,z,col="red", nlevels=15, levels=c(0,1,2,3,4,5,10,15,20,30,40,50,60,80,100))

3.10

dat <- read.csv("applicant.csv",head=T)
#以15项自变量绘制星图
stars(dat[,-1])

#以G1,G2,G3,G4,G5为星图的轴
attach(dat)
dat$G1 <- (SC+LC+SMS+DRV+AMB+GSP+POT)/7
dat$G2 <- (FL+EXP+SUIT)/3
dat$G3 <- (LA+HON+KJ)/3
dat$G4 <- AA
dat$G5 <- APP
stars(dat[,c(17:21)],full=F,draw.segments=T,key.loc=c(5,0.5),mar=c(2,0,0,0))

从图中可以看出，前6名应聘者是：7，8，9，23，39，40