User input and output path of files in R - r

Question

I am aiming to write an R script that would take the user path for the file and output name of the file. This will be followed by its processing and then output being stored in that file.
Normally, if I had to break this code on R studio it will look like this:
d<- read.table("data.txt" , header =T)
r<-summary(d)
print(r)
the output that is being displayed is also to be written in output file.
where data.txt is
1
2
3
4
45
58
10
What I would like to do is to put the code in a file called script.R and then run it as follows
R script.R input_file_path_name output_file_name
Could anyone spare a minute or two and help me out.
Many thanks in advance.

Answer 1

The most natural way to pass arguments from the command line is to use the function commandArgs. This function scans the arguments which have been supplied when the current R session was invoked. So creating a script named sillyScript.R which starts with
#!/usr/bin/env Rscript
args = commandArgs(trailingOnly=TRUE)
and running the following command line
Rscript --vanilla sillyScript.R iris.txt out.txt
will create a string vector args which contains the entries iris.txt and out.txt.
Use the args[1] and args[2] vector as the input and outputfile paths.
https://www.r-bloggers.com/passing-arguments-to-an-r-script-from-command-lines/

Answer 2

You can consider this method:
script<-function(input_file){
input_file<-read.table("data.txt", header=T)
r<- summary(input_file)
return(r)}
If you want to manually choose the input file location you can use:
read.table(file.choose(),header=T)
Just executing the script with the input name is sufficient to return the desired output. For eg,
output_file<-script(input_file)
If you also want to export the data from R, you can modify the script as follows:
script<-function(input_file,output_file_name){
input_file<-read.table("data.txt", header=T)
r<- summary(input_file)
write.table(r,paste0(output_file_name,".txt",collapse="")
return(r)}
You have to use file name within inverted commas:
> vector<- script(input_file,"output_file_name")
By default, the output will be exported to current R directory. You can also specify output file location by putting the file location before output file_name within the script:
write.table(r,paste0("output_location",output_file_name,".txt",collapse="")