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Expand Compositional Bounds into a Valid Grid

gc_expand_bounds.Rd

Generate a grid of valid compositions from component constraints. Uses expand.grid() to create combinations of sequential component values within specified bounds, then filters to rows where component sums equal the target sum (within floating-point tolerance).

Usage

gc_expand_bounds(constraints, step = 0.1, target_sum = 100, tol = 1e-06)

Arguments

constraints

A named list of lists or data frame containing min and max for each component. Example: list(SAND = list(min = 0, max = 40), SILT = list(min = 50, max = 80), CLAY = list(min = 10, max = 20)).

step

Numeric resolution for the grid sequences (default 0.1).

target_sum

Numeric constant sum for valid compositions (default 100).

tol

Floating-point tolerance for sum constraint (default 1e-6).

Value

A data frame where columns are components and rows are valid compositions summing to target_sum.

Details

This function performs:

  1. Validation that min values do not sum to more than target_sum

  2. Dynamic sequence generation for each component based on bounds

  3. Cartesian product expansion via expand.grid()

  4. Filtering to compositions with sum approximately equal to target_sum

Examples

# Define sand, silt, clay bounds
constraints <- list(
  SAND = list(min = 0, max = 40),
  SILT = list(min = 50, max = 80),
  CLAY = list(min = 10, max = 20)
)

# Expand with 1% resolution
grid <- gc_expand_bounds(constraints, step = 1.0, target_sum = 100)
nrow(grid)
#> [1] 341
head(grid)
#>   SAND SILT CLAY
#> 1   40   50   10
#> 2   39   51   10
#> 3   38   52   10
#> 4   37   53   10
#> 5   36   54   10
#> 6   35   55   10