first week
##Factors x<-factor(c("yes","yes","no", "yes", "no")) x table(x) unclass(x) attributes("levels")
##factors x<-factor(c("yes","yes","no", "yes", "no")) levels=(c("not","yes")) x
x<-c(1,2,NA,10,3) is.na(x)
##data frames x<-data.frame(foo=1:4, bar=c(T,T,F,F)) x nrow(x) ncol(x)
##names attributes x<-1:3 names(x) names (x)<-c("foo","bar","norf") x names(x)
x<-list(a=1,b=2,c=3) x
m<-matrix(1:4,nrow=2,ncol=2) m dimnames(m)<-list(c("a","b"),c("c","d")) m
##dput-ting R objects y<-data.frame(a=1,b="a") dput(y) dput(y,file="y.R") new.y<-dget("y.R") new.y
##subsetting x<-c("a","b","c","c","d","a") x[1] x[2] x[3:4] x[1:5] x[x>"a"] x[x>"b"] x[x>"d"] x[x<"d"]
##subsetting a logical vector u<-x>"a" u x[u]
##subsetting lists x<-list(foo=1:4,bar=0.6) x[1] x$foo
x[[1]] x$bar x[1]
##subsetting lists-multiple elements of a list x<-list(foo=1:4, bar=0.6, baz="hello") x[c(1,3)]
##subsetting lists-2*[] x<-list(foo=1:4, bar=0.6, baz="hello") name<-"foo" x[[name]] x$name x$foo
##subsetting lists-2*[]-take an integer sequence x<-list(a=list(10,12,14), b=c(3.14, 2.81)) x[[c(1,3)]] x[[1]][[3]]
x[c(2,1)]
##subsetting Matrices x<-matrix(1:6,2,3) x[1,2] print(matrix) x x[1,3] x[2,3]
##subsetting Matrices-extracting single elements x<-matrix(1:6,2,3) x[1,2] x[1,2,drop=FALSE]
##subsetting Matrices-extracting single column or rows x<-matrix(1:6,2,3) x[1, ] x[1, ,drop=FALSE] x[ ,1] x[ ,1,drop=FALSE]
##subsetting with names x<-list(sardvark=1:5) x$s x[["s"]] x[["s",exact=FALSE]]
##subsetting=removing NA Values x<-c(1,2,NA,4,NA,5) other<-is.na(x) x[!other] other
x<-c(1,2,NA,4,NA,5) y<-c("NA","b","NA","d","NA","f") nice<-complete.cases(x,y) nice x[nice] y[nice] x y
##Vectorized operations x<-1:4 y<-6:9 x+y x>2 x>=2 y==8
##vectorized operations-matrices x<-matrix(1:4,2,2) y<-matrix(rep(10,4),2,2) y xy x/y x%%y
##Quiz 1 x<-4 class(x) x<-c(4,"a",TRUE) class(x) x<-c(1,3,5) y<-c(3,2,10) cbind(x,y) x<-list(2,"a","b",TRUE) x[[2]] x<-1:4 y<-2 x+y x<-c(3,5,1,10,12,6) x[x<6]=0 print(x[x<6]=0)
hw1_data x<-hw1_data x[ ,2] x[2, ] x[3, ] x[1:2, ]
#Loop x<-c("a","b","c","d") for(i in 1:4){print(x[i])} for(i in seq_along(x)){print(x[i])} for(letter in x){print(letter)} count<-0 while(count< 10){print(count)count<-count+1}
z<-5 while(z>=3&&z<=10){print(z)} coin<-rbinom(1,1,0.5) if (coin==1{##random walk z<z+1} else{ z<-z-1}})
x0<-1 tol<-1e-8 repeat{x1<-computeEstumate() if(abs(x1-x0)<tol){break}else{x0<-x1}}