Create a data frame for Crossover design

Usage

df.cod(treatments, label, squares)

treatments: An integer-valued vector specifying the treatment structure, in which the length of the vector indicates the number of treatment factors, and each value represents the number of levels for each factor. A maximum of two factors is allowed, and they are arranged in a factorial design. For instance, treatments = n specifies one treatment factor with n levels, and treatments=c(2,3) creates a "2x3" factorial design of two treatment factors with 2 and 3 levels, respectively.
label: Optional. A list of character vectors specifying the names of treatment factors and factor levels. Each vector in the list represents a treatment factor, where the name of the vector specifies the name of the factor, and the values in the vector are the labels for that factor's levels. If not provided, factors and levels for one and two treatment factors are labeled as list(trt = c("1", "2", ...)) and list(facA = c("1", "2", ...), facB = c("1", "2", ...)), respectively.
squares: The number of replicated squares. By default, 1, i.e., no replicated squares.

a data.frame with columns for treatment factors, individuals (row block factor), period (column block factor), and squares