read files & set file names in the same dplyr pipe - r

Question

This is a tricky dplyr & purrr question
I want to simplify the following code into one dplyr pipe:
filenames <- list.files(path = data.location, pattern = "*.csv") %>%
map_chr(function(name) gsub(paste0('(.*).csv'), '\\1', name))
files.raw <- list.files(path = data.location, pattern = "*.csv", full.names = TRUE) %>%
map(read_csv) %>%
setNames(filenames)
I tried to do this solution but it failed because the filenames must be used with full path (full.names = TRUE) for read_csv() but I want to assign the filenames without the full path.
In other words, this worked - but only with full path in filenames:
list.files(path = data.location, pattern = "*.csv", full.names = TRUE) %>%
{ . ->> filenames } %>%
map(read_csv) %>%
setNames(filenames)
but this didn't:
list.files(path = data.location, pattern = "*.csv", full.names = TRUE) %>%
{ map_chr(., function(name) gsub(paste0(data.location, '/(.*).csv'), '\\1', name)) ->> filenames } %>%
map(read_csv) %>%
setNames(filenames)
Is there a way to make the map_chr work with the save (->> filenames), or is there an even simpler way to completely avoid saving to a temporary variable (filenames)?

Answer 1

To do it in one pipeline without intermediate values, and similar to #Ronak Shah, why not set the names first, then read in the CSVs? Ronak nests the setNames call, but it can be put it in the pipeline to make it more readable:
library(tidyverse)
list.files(path = data.location, pattern = "*.csv", full.names = TRUE) %>%
setNames(., sub("\\.csv$", "", basename(.))) %>%
map(read_csv)

Answer 2

We can do this with only tidyverse functions
library(readr)
library(purrr)
library(dplyr)
all_files <- list.files(path = data.location, pattern = "*\\.csv", full.names = TRUE)
map(all_files, read_csv) %>%
set_names(str_remove(basename(all_files), "\\.csv$"))

Answer 3

Try using this method :
all_files <- list.files(path = data.location, pattern = "*.csv", full.names = TRUE)
purrr::map(all_files, readr::read_csv) %>%
setNames(sub("\\.csv$", "", basename(all_files)))
Here, we first get complete path of all files, use it to read it using read_csv. We can use basename to get only file name and remove "csv" from it and assign names using setNames.
To do this in one-pipe, we can do
list.files(path = data.location, pattern = "*.csv", full.names = TRUE) %>%
{setNames(map(., read_csv), sub("\\.csv$", "", basename(.)))}

Answer 4

Inspired by
the below answer by #Ronak Shah
the intermediary assignment suggested by #G. Grothendiek here
I put together the following solution which
combines the reading and naming of files into one dplyr pipe (my initial goal)
makes the code more intuitive to read (my always implicit goal) - important for collaborators or in general.
So here's my one-in-all dplyr pipe:
list.files(path = data.location, pattern = "*.csv", full.names = TRUE) %>%
{ filenames <<- . } %>%
map(read_csv) %>%
setNames(filenames %>% basename %>% map(~gsub(paste0('(.*).csv'), '\\1', .x)))
The only tricky part in the above solution is to use the assignment operator <<- as <- would not work. If you want to use the latter, you can do so by putting the whole second section into brackets - also suggested by #G. Grothendieck in the above post:
list.files(path = data.location, pattern = "*.csv", full.names = TRUE) %>%
{
{ filenames <- . } %>%
map(read_csv) %>%
setNames(filenames %>% basename %>% map(~gsub(paste0('(.*).csv'), '\\1', .x)))
}