Question

Error saying "Error in map(.x, .f, ...) : argument ".x" is missing, with no default" in R

This is my code:

url_base <- "https://cran.r-project.org/web/packages/available_packages_by_name.html"
map_df(, function(i){
                page <- read_html(sprintf(url_base,i))
                data.frame(IssueID = html_text(html_nodes(page,"h1")),
                       heading = html_text(html_nodes(page,"td")),
                       description = html_text(html_nodes(page,"td")))
}) -> packages

Answer 1

There is small mistake in your code. map_df() should have two parameters. number of iterations and the function. In your case number of iterations is missing. 

map_df(1:10, function(i))

something like this