My program takes a data.frame and crunches the numbers. At one point, values from j-th column are multiplied by a predefined values that depends on the column name (species name, actually - it's en ecological index). So far, I've been providing these values via a second data.frame by matching column names. What would be an efficient way of integrating fixed variable values within a function? I would like my program to be as portable as possible, without the need for a second data.frame file.