##question1###
setwd(“G:/Rexam20174710426”)
a<-2
b<-0
c<-1
d<-7
e<-4
f<-7
g<-1
h<-0
i<-4
j<-2
k<-6
o<-NA#12个变量
var<-c(a,b,c,d,e,f,j,h,i,j,k,o)#合并变量
var
sum.var<-sum(var,na.rm=TRUE)
sum.var
mean.var<-mean(var,na.rm=TRUE)
mean.var
length.var<-length(var)
length.var
###question2###
setwd(“G:/Rexam20174710426”)
MyIDmatrix<-matrix(nrow=4,ncol=3)
MyIDmatrix[,1]<-c(2,0,1,7)
MyIDmatrix[,2]<-c(4,7,1,0)
MyIDmatrix[,3]<-c(4,2,6,NA)#给矩阵赋值
colnames(MyIDmatrix)<-c(“Year”,“Area”,“Number”)#给矩阵加名字
MyIDmatrix
write.table(MyIDmatrix,file=“MyIDmatrix.txt”)#写出文件
class(MyIDmatrix)
MyIDdf<-read.table(file=“MyIDmatrix.txt”,header = T)#读入文件
class(MyIDdf)
names(MyIDdf)
str(MyIDdf)#查看属性
MyIDdf
###question3###
setwd(“G:/Rexam20174710426”)
MyIDdfR3<-rbind(MyIDdf,MyIDdf,MyIDdf)
MyIDdfR3
dim(MyIDdfR3)#12行3列数据框
MyIDdfR3[3,3]<-5
MyIDdfR3[11,3]<-7#变成我前面同学，我，我后面同学的学号
MyIDdfR3#新数据框
MyIDdfR3
r
o
w
s
u
m
<
−
r
o
w
S
u
m
s
(
M
y
I
D
d
f
R
3
,
n
a
.
r
m
=
T
R
U
E
)
M
y
I
D
d
f
R
3
<
−
M
y
I
D
d
f
R
3
[
o
r
d
e
r
(
M
y
I
D
d
f
R
3
rowsum<-rowSums(MyIDdfR3,na.rm=TRUE) MyIDdfR3<-MyIDdfR3[order(MyIDdfR3
rowsum<−rowSums(MyIDdfR3,na.rm=TRUE)MyIDdfR3<−MyIDdfR3[order(MyIDdfR3rowsum),]
MyIDdfR3
###question4###
setwd(“G:/Rexam20174710426”)
is.na(MyIDdfR3[-1,-1])#这个返回的是布尔向量
which(is.na(-MyIDdfR3),arr.ind = TRUE)#找出NA所在行列，共有3个
###question5###
setwd(“G:/Rexam20174710426”)
data()#列出所有可用数据集
View(cars)#直接看表
names(cars)
str(cars)
pdf.options(family=“GB1”)
pdf(file=“YourID.pdf”)
op<-par(mfrow=c(1,2),mar=c(5,5,3,2))#设置面板
#左图
plot(x=cars
s
p
e
e
d
,
y
=
c
a
r
s
speed,y=cars
speed,y=carsdist,xlab=“Speed”,ylab=“Distance”,pch=16)#实心点
#M.Loess<-loess(dist~speed,data=cars)
#Fit<-fitted(M.Loess)
#Ord1<-order(carsKaTeX parse error: Expected 'EOF', got '#' at position 8: speed) #̲lines(carsspeed[Ord1],Fit[Ord1],lwd=2,lty=1)#拟合回归线
abline(lm(dist~speed,data=cars), lwd=3, col=1)#线性回归
#右图
cars
l
e
i
b
i
e
<
−
"
"
c
a
r
s
leibie<-"" cars
leibie<−""carsleibie[which(carsKaTeX parse error: Expected 'EOF', got '&' at position 10: speed>=0 &̲ carsspeed<=10)]=“L”
cars
l
e
i
b
i
e
[
w
h
i
c
h
(
c
a
r
s
leibie[which(cars
leibie[which(carsspeed>10 & cars
s
p
e
e
d
<
=
20
)
]
=
"
M
"
c
a
r
s
speed<=20)]="M" cars
speed<=20)]="M"carsleibie[which(carsKaTeX parse error: Expected 'EOF', got '&' at position 10: speed>20 &̲ carsspeed<=30)]=“H”
cars
l
e
i
b
i
e
<
−
f
a
c
t
o
r
(
c
a
r
s
leibie<-factor(cars
leibie<−factor(carsleibie,c(“L”,“M”,“H”))#需要设置因子水平
boxplot(dist~leibie,data=cars,xlab=“Speed”,ylab=“Distance”)
par(op)#关闭par
dev.off()
pdf.options(reset = TRUE)
