Combining a list of data frames into a new data frame in R

Question

This is a 3rd edit to the question (leaving below thread just in case):

The following code makes some sample data frames, selects those with "_areaX" in the title and makes a list of them. The goal is then to combine the data frames in the list into 1 data frame. It almost works...

Area1 <- 100
Area2 <- 200
Area3 <- 300
Zone <- 3

a1_areaX <- data.frame(Area1)
a2_areaX <- data.frame(Area2)
a3_areaX <- data.frame(Area3)
a_zoneX <- data.frame(Zone)

library(dplyr)   
pattern = "_areaX"
df_list <- mget(ls(envir = globalenv(), pattern = pattern))
big_data = bind_rows(df_list, .id = "FileName")

The problem is the newly created data frame looks like this:

And I need it to look like this:

File Name	Area measurement
a1_areaX	100
a2_areaX	200
a3_areaX	300

Below are my earlier attempts at asking this question. Edited from first version:

I have csv files imported into R Global Env that look like this (I'd share the actual file(s) but there doesn't seem to be a way to do this here):

They all have a name, the above one is called "s6_section_area". There are many of them (with different names) and I've put them all together into a list using this code:

pattern = "section_area"
section_area_list <- list(mget(grep(pattern,ls(globalenv()), value = TRUE), globalenv()))

Now I want a new data frame that looks like this, put together from the data frames in the above made list.

File Name	Area measurement
a1_section_area	a number
a2_section_area	another number
many more	more numbers

So, the first column should list the name of the original file and the second column the measurement provided in that file.

Hope this is clearer - Not sure how else to provide reproducible example without sharing the actual files (which doesn't seem to be an option).

addition to edit: Using this code

section_area_data <- bind_rows(section_area_list, .id = "FileName")

I get (it goes on and on to the right)

I'm after a table that looks like the sample above, left column is file name with a list of file names going down. Right column is the measurement for that file name (taken from original file).

Answer 1

Note that in your list of dataframes (df_list) all the columns have different names (Area1, Area2, Area3) whereas in your output dataframe they all have been combined into one single column. So for that you need to change the different column names to the same one and bind the dataframes together.

library(dplyr)
library(purrr)

result <- map_df(df_list, ~.x %>% 
                  rename_with(~"Area", contains('Area')), .id = 'FileName')
result

#  FileName Area
#1 a1_areaX  100
#2 a2_areaX  200
#3 a3_areaX  300