I am doing a series of intricate data manipulations and in doing so I create a series of dataframes from one "source" dataframe and dynamically name all my "subset" dataframes. They all have the same structure (columns) and I want to bind them together.

The challenge I have is that I can't seem to get the syntax for binding right after I dynamically name/create these dataframes.

So to create my "subset" dataframes I get the desired data into a dataframe called df_master and name it using assign. I do this inside of a for loop so I end up with 10 subset dataframes. Pseudo code looks like this:

for (i in 1:10){

    .... do some stuff ...

    master_df <- save into a df

    assign(paste0("df_months_", i), df_master)  # dynamically (re) name df_master

    }

This works fine and I get my 10 dataframes names df_months_1, df_months_2 , etc.

The trouble comes in when I want to bind. This post recommends binding multiple dataframes using do.call. In order to do that I need to put my "subset" dataframes in a list and then use do.call and rbind. This is the part I cant get right. I think I need a list of the subset dataframes themselves. But I can't seem to create that list.

Per the linked solution I need:

new_df <- do.call("rbind", list(df_months_1, df_months_2, ...)

Not sure how to create that list given that I am dynamically creating names.

CodePudding user response：

As we have create multiple objects in the global env (not recommended), check those objects in the global env with ls with a regex as pattern

ls(pattern = "^df_months_\\d $")

It returns a vector of object names that matches the pattern - df_months_ from the start (^) of the string followed by one or more digits (\\d ) till the end ($) of the string

Now, we get the values of the objects. For >=1 objects, use mget which returns a key/value pair as a named list.

mget(ls(pattern = "^df_months_\\d $"))

Then, we use rbind within do.call to bind the elements of the list

do.call(rbind, mget(ls(pattern = "^df_months_\\d $")))