Introduction to Biological Data Analysis


TP 2: Data structures in R

Prof. Patrick Meyer

BioSys Lab - Université de Liège

Matrices

  1. y <- matrix(45:64, nr=5, byrow=TRUE)

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  2. Matrix of 5 columns, removing third column, then matrix 4X4 of ones 
    m <-rbind(matrix(c(10:19,50:59),nc=5,byrow=T),matrix(90:99,nr=2,byrow=T))
m <- m[,-3]
m <- matrix(1,nc=4,nr=4)

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Functions on vectors and matrices 

  1. minmax <- function(vec) {
 c(min(vec),max(vec))
}

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  2. sqrtndec <- function(vec,n){
  sqrt(sort(vec,decreasing=T)[1:n])
}

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  3. valuechar <- function(vec,n){
  paste("the element number ",n, " of the vector is ",vec[n],sep="")
}

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  4. is.sym <- function(mat){
  sum(!(mat==t(mat)))==0
}

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  5. sqrt(apply(mat,2,sum))

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  6. sum(log(apply(mat,1,prod),2))

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Factors

  1. What happens when we type...

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List

  1. What happens when we type...

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  2. count.numeric <- function(liste){
  sum(sapply(liste,is.numeric))
}

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