1)apply function:
It takes 3 arguments matrix,margin and function..
Example:
m<-matrix(c(1,2,3,4),nrow=2,ncol=2)
m
#1 indicates it is applied in row
apply(m,1,sum)
#2 indicates it is applied in column
apply(m,2,sum)
apply(m,2,mean)#2 indicates it is applied in column
apply(m,2,min)#2 indicates it is applied in column
apply(m,1,mean)#1 indicates it is applied in row
2)lapply function:
It takes list and function..
Example 1:
l<-list(a=c(1,2),b=c(3,4),c=c(5,6))
lapply(l,sum)
lapply(l,mean)
Example 2:
x<-c(4,5,9)
x
b<c("RAM","SAM","GAM")
b
3)sapply function:
It is same as lapply except it simplifies result..
It takes list and function..
Example 1:
s<-list(a=c(1,2),b=c(3,4),c=c(5,6))
sapply(l,sum)
sapply(l,mean)
4)tapply function:
We need 3 arguments vector,factor of vector and functions..
age<-c(20,50,78,89,90)
age
gender<-c("m","m","f","m","f")
gender
f<-factor(gender)
f
tapply(age,f,sum)
tapply(age,f,mean)
where age is vector ,f is factor of vector and sum is the function
Note:sum,mean,min,max are predefind function....
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