This function takes one argument, the number of standard deviations within which to accept a particular data point.

## Usage

``within_n_sds(n, ...)``

## Arguments

n

The number of standard deviations from the mean within which to accept a datum

...

Additional arguments to be passed to `within_bounds`

## Value

A function that takes a vector and returns a

`within_bounds` predicate based on the standard deviation of that vector.

## Details

As an example, if '2' is passed into this function, this will return a function that takes a vector and figures out the bounds of two standard deviations from the mean. That function will then return a `within_bounds` function that can then be applied to a single datum. If the datum is within two standard deviations of the mean of the vector given to the function returned by this function, it will return TRUE. If not, FALSE.

This function isn't meant to be used on its own, although it can. Rather, this function is meant to be used with the `insist` function to search for potentially erroneous data points in a data set.

`within_n_mads`

## Examples

``````test.vector <- rnorm(100, mean=100, sd=20)

within.one.sd <- within_n_sds(1)
custom.bounds.checker <- within.one.sd(test.vector)
custom.bounds.checker(105)     # returns TRUE
#> [1] TRUE
custom.bounds.checker(40)      # returns FALSE
#> [1] FALSE

# same as
within_n_sds(1)(test.vector)(40)    # returns FALSE
#> [1] FALSE

within_n_sds(2)(test.vector)(as.numeric(NA))  # returns TRUE
#> [1] TRUE
# because, by default, within_bounds() will accept
# NA values. If we want to reject NAs, we have to
# provide extra arguments to this function
within_n_sds(2, allow.na=FALSE)(test.vector)(as.numeric(NA))  # returns FALSE
#> [1] FALSE

# or in a pipeline, like this was meant for

library(magrittr)

iris %>%
insist(within_n_sds(5), Sepal.Length)
#>     Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
#> 1            5.1         3.5          1.4         0.2     setosa
#> 2            4.9         3.0          1.4         0.2     setosa
#> 3            4.7         3.2          1.3         0.2     setosa
#> 4            4.6         3.1          1.5         0.2     setosa
#> 5            5.0         3.6          1.4         0.2     setosa
#> 6            5.4         3.9          1.7         0.4     setosa
#> 7            4.6         3.4          1.4         0.3     setosa
#> 8            5.0         3.4          1.5         0.2     setosa
#> 9            4.4         2.9          1.4         0.2     setosa
#> 10           4.9         3.1          1.5         0.1     setosa
#> 11           5.4         3.7          1.5         0.2     setosa
#> 12           4.8         3.4          1.6         0.2     setosa
#> 13           4.8         3.0          1.4         0.1     setosa
#> 14           4.3         3.0          1.1         0.1     setosa
#> 15           5.8         4.0          1.2         0.2     setosa
#> 16           5.7         4.4          1.5         0.4     setosa
#> 17           5.4         3.9          1.3         0.4     setosa
#> 18           5.1         3.5          1.4         0.3     setosa
#> 19           5.7         3.8          1.7         0.3     setosa
#> 20           5.1         3.8          1.5         0.3     setosa
#> 21           5.4         3.4          1.7         0.2     setosa
#> 22           5.1         3.7          1.5         0.4     setosa
#> 23           4.6         3.6          1.0         0.2     setosa
#> 24           5.1         3.3          1.7         0.5     setosa
#> 25           4.8         3.4          1.9         0.2     setosa
#> 26           5.0         3.0          1.6         0.2     setosa
#> 27           5.0         3.4          1.6         0.4     setosa
#> 28           5.2         3.5          1.5         0.2     setosa
#> 29           5.2         3.4          1.4         0.2     setosa
#> 30           4.7         3.2          1.6         0.2     setosa
#> 31           4.8         3.1          1.6         0.2     setosa
#> 32           5.4         3.4          1.5         0.4     setosa
#> 33           5.2         4.1          1.5         0.1     setosa
#> 34           5.5         4.2          1.4         0.2     setosa
#> 35           4.9         3.1          1.5         0.2     setosa
#> 36           5.0         3.2          1.2         0.2     setosa
#> 37           5.5         3.5          1.3         0.2     setosa
#> 38           4.9         3.6          1.4         0.1     setosa
#> 39           4.4         3.0          1.3         0.2     setosa
#> 40           5.1         3.4          1.5         0.2     setosa
#> 41           5.0         3.5          1.3         0.3     setosa
#> 42           4.5         2.3          1.3         0.3     setosa
#> 43           4.4         3.2          1.3         0.2     setosa
#> 44           5.0         3.5          1.6         0.6     setosa
#> 45           5.1         3.8          1.9         0.4     setosa
#> 46           4.8         3.0          1.4         0.3     setosa
#> 47           5.1         3.8          1.6         0.2     setosa
#> 48           4.6         3.2          1.4         0.2     setosa
#> 49           5.3         3.7          1.5         0.2     setosa
#> 50           5.0         3.3          1.4         0.2     setosa
#> 51           7.0         3.2          4.7         1.4 versicolor
#> 52           6.4         3.2          4.5         1.5 versicolor
#> 53           6.9         3.1          4.9         1.5 versicolor
#> 54           5.5         2.3          4.0         1.3 versicolor
#> 55           6.5         2.8          4.6         1.5 versicolor
#> 56           5.7         2.8          4.5         1.3 versicolor
#> 57           6.3         3.3          4.7         1.6 versicolor
#> 58           4.9         2.4          3.3         1.0 versicolor
#> 59           6.6         2.9          4.6         1.3 versicolor
#> 60           5.2         2.7          3.9         1.4 versicolor
#> 61           5.0         2.0          3.5         1.0 versicolor
#> 62           5.9         3.0          4.2         1.5 versicolor
#> 63           6.0         2.2          4.0         1.0 versicolor
#> 64           6.1         2.9          4.7         1.4 versicolor
#> 65           5.6         2.9          3.6         1.3 versicolor
#> 66           6.7         3.1          4.4         1.4 versicolor
#> 67           5.6         3.0          4.5         1.5 versicolor
#> 68           5.8         2.7          4.1         1.0 versicolor
#> 69           6.2         2.2          4.5         1.5 versicolor
#> 70           5.6         2.5          3.9         1.1 versicolor
#> 71           5.9         3.2          4.8         1.8 versicolor
#> 72           6.1         2.8          4.0         1.3 versicolor
#> 73           6.3         2.5          4.9         1.5 versicolor
#> 74           6.1         2.8          4.7         1.2 versicolor
#> 75           6.4         2.9          4.3         1.3 versicolor
#> 76           6.6         3.0          4.4         1.4 versicolor
#> 77           6.8         2.8          4.8         1.4 versicolor
#> 78           6.7         3.0          5.0         1.7 versicolor
#> 79           6.0         2.9          4.5         1.5 versicolor
#> 80           5.7         2.6          3.5         1.0 versicolor
#> 81           5.5         2.4          3.8         1.1 versicolor
#> 82           5.5         2.4          3.7         1.0 versicolor
#> 83           5.8         2.7          3.9         1.2 versicolor
#> 84           6.0         2.7          5.1         1.6 versicolor
#> 85           5.4         3.0          4.5         1.5 versicolor
#> 86           6.0         3.4          4.5         1.6 versicolor
#> 87           6.7         3.1          4.7         1.5 versicolor
#> 88           6.3         2.3          4.4         1.3 versicolor
#> 89           5.6         3.0          4.1         1.3 versicolor
#> 90           5.5         2.5          4.0         1.3 versicolor
#> 91           5.5         2.6          4.4         1.2 versicolor
#> 92           6.1         3.0          4.6         1.4 versicolor
#> 93           5.8         2.6          4.0         1.2 versicolor
#> 94           5.0         2.3          3.3         1.0 versicolor
#> 95           5.6         2.7          4.2         1.3 versicolor
#> 96           5.7         3.0          4.2         1.2 versicolor
#> 97           5.7         2.9          4.2         1.3 versicolor
#> 98           6.2         2.9          4.3         1.3 versicolor
#> 99           5.1         2.5          3.0         1.1 versicolor
#> 100          5.7         2.8          4.1         1.3 versicolor
#> 101          6.3         3.3          6.0         2.5  virginica
#> 102          5.8         2.7          5.1         1.9  virginica
#> 103          7.1         3.0          5.9         2.1  virginica
#> 104          6.3         2.9          5.6         1.8  virginica
#> 105          6.5         3.0          5.8         2.2  virginica
#> 106          7.6         3.0          6.6         2.1  virginica
#> 107          4.9         2.5          4.5         1.7  virginica
#> 108          7.3         2.9          6.3         1.8  virginica
#> 109          6.7         2.5          5.8         1.8  virginica
#> 110          7.2         3.6          6.1         2.5  virginica
#> 111          6.5         3.2          5.1         2.0  virginica
#> 112          6.4         2.7          5.3         1.9  virginica
#> 113          6.8         3.0          5.5         2.1  virginica
#> 114          5.7         2.5          5.0         2.0  virginica
#> 115          5.8         2.8          5.1         2.4  virginica
#> 116          6.4         3.2          5.3         2.3  virginica
#> 117          6.5         3.0          5.5         1.8  virginica
#> 118          7.7         3.8          6.7         2.2  virginica
#> 119          7.7         2.6          6.9         2.3  virginica
#> 120          6.0         2.2          5.0         1.5  virginica
#> 121          6.9         3.2          5.7         2.3  virginica
#> 122          5.6         2.8          4.9         2.0  virginica
#> 123          7.7         2.8          6.7         2.0  virginica
#> 124          6.3         2.7          4.9         1.8  virginica
#> 125          6.7         3.3          5.7         2.1  virginica
#> 126          7.2         3.2          6.0         1.8  virginica
#> 127          6.2         2.8          4.8         1.8  virginica
#> 128          6.1         3.0          4.9         1.8  virginica
#> 129          6.4         2.8          5.6         2.1  virginica
#> 130          7.2         3.0          5.8         1.6  virginica
#> 131          7.4         2.8          6.1         1.9  virginica
#> 132          7.9         3.8          6.4         2.0  virginica
#> 133          6.4         2.8          5.6         2.2  virginica
#> 134          6.3         2.8          5.1         1.5  virginica
#> 135          6.1         2.6          5.6         1.4  virginica
#> 136          7.7         3.0          6.1         2.3  virginica
#> 137          6.3         3.4          5.6         2.4  virginica
#> 138          6.4         3.1          5.5         1.8  virginica
#> 139          6.0         3.0          4.8         1.8  virginica
#> 140          6.9         3.1          5.4         2.1  virginica
#> 141          6.7         3.1          5.6         2.4  virginica
#> 142          6.9         3.1          5.1         2.3  virginica
#> 143          5.8         2.7          5.1         1.9  virginica
#> 144          6.8         3.2          5.9         2.3  virginica
#> 145          6.7         3.3          5.7         2.5  virginica
#> 146          6.7         3.0          5.2         2.3  virginica
#> 147          6.3         2.5          5.0         1.9  virginica
#> 148          6.5         3.0          5.2         2.0  virginica
#> 149          6.2         3.4          5.4         2.3  virginica
#> 150          5.9         3.0          5.1         1.8  virginica

``````