Generate a Gamma Distribution Definition Based on Parameter Estimates

Generates a distribution definition when only parameter estimates are available for gamma distributed parameters. See rgamma for distribution information.

gamma_dist_def(
  shape,
  shape_sd,
  scale,
  scale_sd,
  mean,
  mean_sd,
  sd,
  sd_sd,
  max_value,
  samples
)

Arguments

shape	Numeric, shape parameter of the gamma distribution.
shape_sd	Numeric, standard deviation of the shape parameter.
scale	Numeric, scale parameter of the gamma distribution.
scale_sd	Numeric, standard deviation of the scale parameter.
max_value	Numeric, the maximum value to allow. Defaults to 120. Samples outside of this range are resampled.
samples	Numeric, number of sample distributions to generate.

Value

A data.table definining the distribution as used by dist_skel

Examples

## Using estimated shape and scale
def <- gamma_dist_def(shape = 5.807, shape_sd = 0.2,
               scale = 0.9, scale_sd = 0.05,
               max_value = 20, samples = 10)
               
print(def)
#>     model    params max_value
#>  1: gamma <list[2]>        20
#>  2: gamma <list[2]>        20
#>  3: gamma <list[2]>        20
#>  4: gamma <list[2]>        20
#>  5: gamma <list[2]>        20
#>  6: gamma <list[2]>        20
#>  7: gamma <list[2]>        20
#>  8: gamma <list[2]>        20
#>  9: gamma <list[2]>        20
#> 10: gamma <list[2]>        20

def$params[[1]]
#> $alpha
#> [1] 6.446901
#> 
#> $beta
#> [1] 1.168393
#> 

## Using mean and sd
def <- gamma_dist_def(mean = 3, mean_sd = 0.5,
               sd = 3, sd_sd = 0.1,
               max_value = 20, samples = 10)
               
print(def)
#>     model    params max_value
#>  1: gamma <list[2]>        20
#>  2: gamma <list[2]>        20
#>  3: gamma <list[2]>        20
#>  4: gamma <list[2]>        20
#>  5: gamma <list[2]>        20
#>  6: gamma <list[2]>        20
#>  7: gamma <list[2]>        20
#>  8: gamma <list[2]>        20
#>  9: gamma <list[2]>        20
#> 10: gamma <list[2]>        20

def$params[[1]]
#> $alpha
#> [1] 0.9309454
#> 
#> $beta
#> [1] 0.3262709
#>