Scale to unit range.

scaleToUnit scales the columns of a numeric matrix to the unit range.

scaleToUnit(x, min = 0, max = 1, solveSingular = TRUE)

Arguments

x	a numeric matrix
min	the minimum in each dimension to scale to (defaults to 0)
max	the maximum in each dimension to scale to (defaults to 1)
solveSingular	if TRUE, constant columns will be transformed to the mean of min and max, not to NaN, as would result from a straighforward implementation

Value

Scaled x. The desired minimum and maximum values are returned as attributes min and max, respectively. The minimum/maximum values of x are returned as attributes min_x and max_x, respectively. The function used to transform a row in x to the desired range is returned as the tx attribute. The inverse transform can be find in the txInv attribute.

Examples

# scale the \code{iris} data set
x <- iris[, 1:4]
summary(x)
#>   Sepal.Length    Sepal.Width     Petal.Length    Petal.Width   
#>  Min.   :4.300   Min.   :2.000   Min.   :1.000   Min.   :0.100  
#>  1st Qu.:5.100   1st Qu.:2.800   1st Qu.:1.600   1st Qu.:0.300  
#>  Median :5.800   Median :3.000   Median :4.350   Median :1.300  
#>  Mean   :5.843   Mean   :3.057   Mean   :3.758   Mean   :1.199  
#>  3rd Qu.:6.400   3rd Qu.:3.300   3rd Qu.:5.100   3rd Qu.:1.800  
#>  Max.   :7.900   Max.   :4.400   Max.   :6.900   Max.   :2.500  
x2 <- scaleToUnit(x)
summary(x2)
#>   Sepal.Length     Sepal.Width      Petal.Length     Petal.Width     
#>  Min.   :0.0000   Min.   :0.0000   Min.   :0.0000   Min.   :0.00000  
#>  1st Qu.:0.2222   1st Qu.:0.3333   1st Qu.:0.1017   1st Qu.:0.08333  
#>  Median :0.4167   Median :0.4167   Median :0.5678   Median :0.50000  
#>  Mean   :0.4287   Mean   :0.4406   Mean   :0.4675   Mean   :0.45806  
#>  3rd Qu.:0.5833   3rd Qu.:0.5417   3rd Qu.:0.6949   3rd Qu.:0.70833  
#>  Max.   :1.0000   Max.   :1.0000   Max.   :1.0000   Max.   :1.00000  

# transform explicitly:
x2[1, ]
#> Sepal.Length  Sepal.Width Petal.Length  Petal.Width 
#>   0.22222222   0.62500000   0.06779661   0.04166667 
attr(x2, 'tx')(iris[1, 1:4])
#>   Sepal.Length Sepal.Width Petal.Length Petal.Width
#> 1    0.2222222       0.625   0.06779661  0.04166667

# inverse transform:
y <- cbind(1:4,1)
y
#>      [,1] [,2]
#> [1,]    1    1
#> [2,]    2    1
#> [3,]    3    1
#> [4,]    4    1
y2 <- scaleToUnit(y ,min = 0, max = 1)
y2
#>           [,1] [,2]
#> [1,] 0.0000000  0.5
#> [2,] 0.3333333  0.5
#> [3,] 0.6666667  0.5
#> [4,] 1.0000000  0.5
#> attr(,"min_x")
#> [1] 1 0
#> attr(,"max_x")
#> [1] 4 2
#> attr(,"min")
#> [1] 0
#> attr(,"max")
#> [1] 1
#> attr(,"tx")
#> function (x) 
#> txImpl(x, minX, maxX, min, max)
#> <bytecode: 0x55dfb7dec150>
#> <environment: 0x55dfb75b5640>
#> attr(,"txInv")
#> function (x) 
#> txInvImpl(x, minX, maxX, min, max)
#> <bytecode: 0x55dfb7dec5b0>
#> <environment: 0x55dfb75b5640>
y3 <- attr(y2, 'txInv')(y2)
y3
#>      [,1] [,2]
#> [1,]    1    1
#> [2,]    2    1
#> [3,]    3    1
#> [4,]    4    1