I am trying to create an app where user can upload data perform analysis using a formulae and plot using ggplot2. The formula should looks something like f1 and runs perfectly fine when there is only one grouping variable. However, I would like to add multiple grouping variables and then run the analysis. So might looks something like f2. And this input will be from the sever where select input multiple=True has been enabled.
f1 = as.formula(paste(input$dv,"~",input$time,"|",input$id))
server select input
selectInput('group','grouping var'," ",selected="",multiple = TRUE)
Finally after the analysis I want to use the same grouping variable to facet in ggplot2.