Different functions over a list of columns and generate new column names automatically with data.table

Question

I have a section in my Shiny app that generates a list.

names of the list are column names of the dataframe we will calculate on, list items contain the ca

Answer 1

To turn Uwe's answer into a function I did this:

Summarystats <- function(statlist, dataframe, group) { 
    statlist %>%
        names() %>% 
        lapply(
            function(.col) lapply(
                statlist[[.col]], 
                function(.fct) sprintf("%s.%s = %s(%s)", .col, .fct, .fct, .col))) %>% 
        unlist() %>% 
        paste(collapse = ", ") %>% 
        sprintf("as.data.table(dataframe)[, .(%s), by = group]", .) %>% 
        parse(text = .) %>% 
        eval()
    }

Now I can call:

Summarystats(mylist, mtcars, 'cyl')

allowing me to call a summary table for whichever dataframe and grouping the user wants in my Shiny App.