a = rnorm(20)

a[1:10]

a[-2]

seq(-2,2,by=0.2)

rep(1,10)



a = c(1:12)


rep(a, 3)




mymatrix = matrix(a,3,4,byrow=T)

mymatrix = matrix(a,3,4)


apply(mymatrix,1,mean)

apply(mymatrix,2,sum)


apply(mymatrix,1,max)

mymatrix[1:2, ]

mymatrix[-1,]

mymatrix[,2:4]

dim(mymatrix)



# write your own function 

myfunc
=function(a){b=mean(a);c=sd(a);d=a+2;outcome=list(b,c,d);return(outcome)}

a=rnorm(10)

myfunc(a)
one sample t test

# loop function

x= c(1:10)

for (i in 1:10){x[i]=x[i]+10}

x


#plot

plot(x,y) #scatterplot


plot(x,y,type="l") # line

plot (x,y,type="b") # both points and line

plot(x,y,pch="+") # plotting character 


plot(x,y,type="l",lty=3,col=2) # line type and color


plot(x,y, xlab="mid term test score",ylab="final test score",
main="relation between midterm and final scores")

pairs(mymatrix) # pairwise scatter plot

coplot(a~b|c) # plot a vs b at given level of c