# rowMeans2: Form row means taking into account a minimum number of values... In ryouready: Companion to the Forthcoming Book - R you Ready?

## Description

In the construction of psychometric scales the calculation of a value is sometimes only desired if a minimum number of items contain values. In SPSS it is possible to calculate a mean value only if a minimum number of values are supplied by using the syntax MEAN.MIN with MIN being a numeric value. The function `rowMeans2` does the same.

## Usage

 `1` ```rowMeans2(x, w, min = 0, na.rm = TRUE) ```

## Arguments

 `x` A matrix of dataframe whose columns should be averaged. `w` A numerical vector of weights the same length as number of columns in `x`. `min` The minimum number of values required to calculate the mean value. Otherwise return `NA`. `na.rm` A logical value indicating whether `NA` values in `x` should be stripped before the computation proceeds.

## Details

`rowMeans2` is very similary to `rowMeans`. The differences are that `rowMeans2` allows to indicate the minimum number of values that have to be supplied and to weight the columns.

## Value

A vector of means.

## Author(s)

Mark Heckmann

`rowMeans`

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```x <- replicate(3, runif(5)) x[1:3, 1] <- NA # add NAs to data x[1:2, 2] <- NA x[1, 3] <- NA x rowMeans2(x) # the same as rowMeans, except that NAs are allowed rowMeans2(x, min=2) # minimum two values to calculate mean rowMeans2(x, min=3) # minimum three values to calculate mean # returns numeric(0) if x has zero rows d <- x[NULL, ] rowMeans2(d) # weights for each column rowMeans2(x, w=c(1,1,2)) ```

### Example output

```          [,1]       [,2]       [,3]
[1,]        NA         NA         NA
[2,]        NA         NA 0.32754336
[3,]        NA 0.62029081 0.83242741
[4,] 0.4989461 0.03526793 0.20840393
[5,] 0.7293810 0.19558767 0.06468153
[1]        NA 0.3275434 0.7263591 0.2475393 0.3298834
[1]        NA        NA 0.7263591 0.2475393 0.3298834
[1]        NA        NA        NA 0.2475393 0.3298834
numeric(0)
[1]        NA 0.3275434 0.7617152 0.2377555 0.2635829
```

ryouready documentation built on May 1, 2019, 8:39 p.m.