error when using `get` within a dplyr mutate statement in R

September 6, 2023

I have my R environment with some objects in it.

tmp <- list(1,2,4)
dafa <- data.frame(thing="Yes", 
            value=4)

Lists and Dataframes both come up as list when using:

typeof(get("tmp"))  # list
typeof(get("dafa")) # list

I want to get a dataframe of all the objects in my environment and note whether some of them are dataframes or not using inherits(get(name), "data.frame")

library(tidyverse)
# get a list of all the objects in the environment and 
# store in a table
data_items <- map_dfr(ls(), \(itm){
    data.frame(name=itm, 
               type=typeof(get(itm)), 
               size=object.size(get(itm)))})

# adjust each row to specify if object is a dataframe
data_items %>% rowwise() %>%
mutate(type = ifelse(inherits(get(name), "data.frame"),
                   "data.frame",
                   type))

However, this complains:

Error in get(name) : first argument has length > 1

Even though it’s rowwise, any idea where I’m going wrong?

>Solution :

data.frame(name = ls(),
           class = sapply(mget(ls()), class))
#      name      class
# dafa dafa data.frame
# tmp   tmp       list

A comparable tidyverse solution would be:

library(purrr)

tibble(name = ls(envir = .GlobalEnv),
       class = map_chr(mget(name, envir = .GlobalEnv), class))
#   name  class     
#   <chr> <chr>     
# 1 dafa  data.frame
# 2 tmp   list