# colnth: 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 R Documentation

## 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)
rownth(x,elems, num.of.nths = 1,descending = FALSE,na.rm = FALSE,
index.return = FALSE, parallel = FALSE)
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".

### 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)

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

### Examples

```x <- matrix( rnorm(100 * 100), ncol = 100 )
elems <- sample(1:100,100,TRUE)
system.time( colnth(x,elems) )
system.time( rownth(x,elems) )
x <- rnorm(1000)
nth(x, 500)
sort(x)[500]

x<-elems<-NULL
```

Rfast documentation built on March 18, 2022, 7:41 p.m.