dir()
df<-read.csv("BM.csv")
edit(df)
names(df)
dim(df)
df[9440,3]
df$LBXTHG
df$LBXTHG[23]
df[23,2]
df$LBXTHG[23:30]
df$LBXTHG[23:100]
df$LBXTHG[-50]
z<-rnorm(10)
z
z[1:3]
z[2:5]
c(-2,-3,-4)
i<-c(-2,-3,-4)
i
z[i]
j<-c(4,5,7,9)
z[j]
tf<-c(TRUE,TRUE,FALSE,FALSE,TRUE,TRUE,FALSE,FALSE,TRUE,FALSE)
tf
z
z[tf]
t20<-rep(TRUE,20)
t20
f5<-rep(FALSE,5)
f5
w<-c(t20,f5)
w
w<-rep(c(t20,f5),3)
w
sample(1:10000,size=50,replace=F)
sample(1:10000,size=50,replace=T)
v<-c("Jianling","Yandi","Chenyue")
v
v[1]
v[2]
v[3]
tf
w
z
v
w
z
L<-list(names=v,tf=w,value=z)
L
L[[1]]
L[[2]]
L[[3]]
L$value
L$tf
df
names(df)
hist(df$LBXTHG)
hist(log(df$LBXTHG))
mean(df$LBXTHG)
mean(df$LBXTHG,na.rm=T)
average(df$LBXTHG,na.rm=T)
?mean
v<-df$LBXTHG
v
v
tf<-is.na(v)
tf
v
v[tf]
v[!tf]
!FALSE
tf
r<-v[!tf]
r
r>4
r[r>4]
r[r>10]
history()
history(1000)