find the coefficients in a formula

A reaction formula has reactants and products, separated by <=>, with reactants on the left and products on the right (by convention). Each of those is a plus separated list of reacting compounds and modifiers, with optional coefficients, e.g.: A + 2 B <=> AB2

Usage

match.coefficients(chrv)

Arguments

chrv

a character vector as returned by parse.formula

Value

coefficients, as a vector

Details

Once the formula is split into left and right side, this function determines the coefficients. For the above example, this function returns c(1,2) for the left side and 1 for the right side.

Examples

lapply(uqsa:::parse.formula("A + 2*B <=> AB2"),uqsa:::match.coefficients)
#> Warning: NAs introduced by coercion
#> $reactants
#> [1]  1 NA
#> 
#> $products
#> [1] 1
#>