A vector containing number of variables in each group. For example, the vfit dataset that is provided in the package contains 3 different groups, where the first 7 variables are general covariates (e.g. age, sex, BMI, and etc.), the next 17 variables belong to nutrient (e.g. vitamins B6, B12, C, D, and etc.), and the last 5 variables belong to physical performance and muscle strength. Thus, n.memberships = c(7, 17, 5). If n.memberships = NULL, in the graph visualization all markers are represented same colour.