Use object names as list names in R

问题:

Of course I could name the objects in my list all manually like this:

    #create dfs
    df1<-data.frame(a=sample(1:50,10),b=sample(1:50,10),c=sample(1:50,10))
    df2<-data.frame(a=sample(1:50,9),b=sample(1:50,9),c=sample(1:50,9))
    df3<-data.frame(a=sample(1:50,8),b=sample(1:50,8),c=sample(1:50,8))

    #make them a list
    list.1<-list(df1=df1,df2=df2,df3=df3)

But it makes a lot of work if I have let's say 50 objects with long names. So is there any way to automate this and make the names inside the list the same as the outside objects?

回答1:

Find the names, then call mget.
If there is a pattern to the names of each individual variable, then this is straightforward.

var_names <- paste0("df", 1:3)
mget(var_names, envir = globalenv())  #or maybe envir = parent.frame()

If the naming system is more complicated, you can use regular expressions to find them, using something like

var_names <- ls(envir = globalenv(), pattern = "^df[[:digit:]]+$")

回答2:

If you just want to name a list with names from the environment that share something, in this case 'df':

names(list.1) <- grep("df",ls(),value=TRUE)

If you want to push your environment into a list:

list.1 <- globalenv()
list.1 <- as.list(list.1) 

To reverse the process see ?list2env