Some Matrix Functions
Some matrix functions which are written in Rcpp for speed reasons.
rowMaxs.sirt(matr) # rowwise maximum rowMins.sirt(matr) # rowwise minimum rowCumsums.sirt(matr) # rowwise cumulative sum colCumsums.sirt(matr) # columnwise cumulative sum rowIntervalIndex.sirt(matr,rn) # first index in row nn when matr(nn,zz) > rn(nn) rowKSmallest.sirt(matr, K, break.ties=TRUE) # k smallest elements in a row rowKSmallest2.sirt(matr, K )
matr |
A numeric matrix |
rn |
A vector, usually a random number in applications |
K |
An integer indicating the number of smallest elements to be extracted |
break.ties |
A logical which indicates if ties are randomly
broken. The default is |
The function rowIntervalIndex.sirt searches for all rows n
the first index i for which matr(n,i) > rn(n) holds.
The functions rowKSmallest.sirt and rowKSmallest2.sirt
extract the K smallest entries in a matrix row. For small
numbers of K the function rowKSmallest2.sirt is
the faster one.
The output of rowMaxs.sirt is a list with the elements
maxval (rowwise maximum values) and maxind (rowwise
maximum indices). The output of rowMins.sirt contains
corresponding minimum values with entries minval and
minind.
The output of rowKSmallest.sirt are two matrices:
smallval contains the K smallest values whereas
smallind contains the K smallest indices.
Alexander Robitzsch
The Rcpp code for rowCumsums.sirt is copied from code of
Romain Francois
(https://lists.r-forge.r-project.org/pipermail/rcpp-devel/2010-October/001198.html).
For other matrix functions see the matrixStats package.
############################################################################# # EXAMPLE 1: a small toy example (I) ############################################################################# set.seed(789) N1 <- 10 ; N2 <- 4 M1 <- round( matrix( runif(N1*N2), nrow=N1, ncol=N2), 1 ) rowMaxs.sirt(M1) # rowwise maximum rowMins.sirt(M1) # rowwise minimum rowCumsums.sirt(M1) # rowwise cumulative sum # row index for exceeding a certain threshold value matr <- M1 matr <- matr / rowSums( matr ) matr <- sirt::rowCumsums.sirt( matr ) rn <- runif(N1) # generate random numbers rowIntervalIndex.sirt(matr,rn) # select the two smallest values rowKSmallest.sirt(matr=M1, K=2) rowKSmallest2.sirt(matr=M1, K=2)
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.