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sort(union(xz,z))# xz z setequal(union(xz,z),x)# intersect(1:10,7:50) # # 1:100 , # 1:100 sample(1:100,20,prob=1:100) # pi *10ˆ2 # ? * , pi "*"(pi, "ˆ"(10,2)) # ! pi * (1:10)ˆ-2.3# x = pi * 10ˆ2 x print(x) # (x=pi *10ˆ2) # piˆ(1:5) #
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x=rnorm(200)#200 x hist(x, col = "light blue")# (histogram) rug(x) # stem(x)# x <- rnorm(500) y <- x + rnorm(500) # plot(y˜ x) # a=lm(y˜x) # abline(a,col="red") # abline(lm(y˜x),col="red") print("Hello World!") paste("x = ", min(x)) # demo(graphics)# ( Enter )
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ncol(cars);nrow(cars) #cars dim(cars) #cars # dist ,speed OLS lm(dist ˜ speed, data = cars) # qspeed, cars$qspeed =cut(cars$speed, breaks=quantile(cars$sp include.lowest = TRUE) names(cars) # cars cars[3]# cars[,3] table(cars[3])# is.factor(cars$qspeed) plot(dist ˜ qspeed, data = cars)#
(z=x%*%y) # z1=solve(z) # ,solve(a,b) z1%*%z # , round(z1%*%z,14) # b=solve(z,1:4); b # nrow(x);ncol(x);dim(x)# x=matrix(rnorm(24),4,6) x[c(2,1),]# 2 1 x[,c(1,3)] # 1 0 sum(x[,1]>0) # 1 0 sum(x[,1]<=0) # 1 0 x[,-c(1,3)]# 1 3 x. diag(x) #x
uniroot(f,c(0,2))# # f=function(x) xˆ2+2*x+1 # optimize(f,c(-2,2))# (-2,2)
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LETTERS[1:26]# a=factor(letters[1:10])#letters: a[3]="w" # ! a=as.character(a) # a[3]="w" # a;factor(a) # b=sample(LETTERS[1:26],100,rep=T) table(b) barplot(table(b))# b=factor(b) levels(b) ,
sort(x,decreasing=T)#sort(x,dec=T) x sum(x);length(x)# round(x) # , round(x,0) # round(x,5) 5 fivenum(x) # , quantiles quantile(x) # quantiles, quantile(x, c(0,.33,.66,1)) mad(x) # "median average distance": cummax(x)# cummin(x)# cumprod(x)# cor(x,sin(x/20)) # (correlation)
# ( ) (a=lm(dist ˜ qspeed, data = cars)) summary(a)# ( )
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x <- round(runif(20,0,20), digits=2)# summary(x) # min(x);max(x) # , range(x) median(x) # (median) mean(x) # (mean) var(x) # (variance) sd(x) # (standard deviation), sqrt(var(x)) # rank(x) # (rank) order(x)# x order(x,decreasing = T)# x x[order(x)] # sort(x) sort(x) # : x
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y=iris;y[1:5,];str(y) #iris R write.table(y,"test.txt",s=F)# # . header=F, w=read.table("test.txt",header=T) str(w) # write.csv(y,"test.csv")# csv v=read.csv("test.csv")# csv str(v) #
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x=1:100# 1,2,...,100 x (x=1:100) # , sample(x,20)# x 20 set.seed(0);sample(1:10,3)# # 1 200 1000 z=sample(1:200,1000) z[1:10]# z y=c(1,3,7,3,4,2) z[y]# y z (z=sample(x,100,rep=T))# x (z1=unique(z)) length(z1)#z xz=setdiff(x,z) #x z --
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