nth: Column and row-wise nth smallest value of a matrix/vector

In Rfast: A Collection of Efficient and Extremely Fast R Functions

Column and row-wise nth smallest value of a matrix/vector

Description

Column and row-wise nth smallest value of a matrix/vector.

Usage

colnth(x,elems, num.of.nths = 1,descending = FALSE,na.rm = FALSE,
	index.return = FALSE, parallel = FALSE, cores = 0)
rownth(x,elems, num.of.nths = 1,descending = FALSE,na.rm = FALSE,
	index.return = FALSE, parallel = FALSE, cores = 0)
nth(x, k, num.of.nths = 1,descending = FALSE,index.return = FALSE,na.rm = FALSE)

Arguments

x	A matrix with the data.
elems	An integer vector with the kth smallest number to be returned for each column/row.
k	The kth smallest/biggest number to be returned.
num.of.nths	The number of the returned nths. By default is 1. Not use with argument parallel, for now.
descending	A boolean value (TRUE/FALSE) for descending order (biggest number). By default is ascending (smallest number).
index.return	Return the index of the kth smallest/biggest number.
parallel	Do you want to do it in parallel in C++? TRUE or FALSE only for col-row wise.
na.rm	TRUE or FAlSE for remove NAs if exists. Only for function "nth".
cores	Number of cores to use for parallelism. Valid only when argument parallel is set to TRUE. Default value is 0 and it means the maximum supported cores.

Details

The functions is written in C++ in order to be as fast as possible.

Value

For "colnth" , "rownth": A vector with the column/row nth

For "nth": The nth value.

Author(s)

Manos Papadakis <[e-mail]>

R implementation and documentation: Michail Tsagris <[e-mail]> and Manos Papadakis <[e-mail]>.

See Also

Median, colMedians, colMeans (buit-in R function)

Examples

x <- matrix( rnorm(100 * 100), ncol = 100 )
elems <- sample(1:100,100,TRUE)
colnth(x,elems)
rownth(x,elems)
x <- rnorm(1000)

nth(x, 500)
#sort(x)[500]

x<-elems<-NULL

Rfast documentation built on Nov. 9, 2023, 5:06 p.m.