write a data.frame to an R file-CodePudding

I wish to write a data.frame from one R file to another R file using base R. So far I have tried cat, capture.output, write.table and sink. I found suggested solutions for capture.output and write.table here:

writing a data.frame using cat

However, I have not been able to obtain an ideal solution. write.table comes the closest but returns an unwanted warning message.

Here is the data.frame in the source R file:

my.df <- data.frame(scenario  = 3333,
                    AA        = 200,
                    BB        = 999,
                    CC        = 444,
                    DD        = 7)

Here is the desired appearance in the recipient R file except I want the name to be my.df, not desired.format:

desired.format <- read.table(text = '
             scenario    AA    BB   CC  DD
                 3333   200   999  444   7
', header = TRUE, stringsAsFactors = FALSE)

Here is the full code for the source R file except for the setwd() statement:

R.file <- 'my_R_file.R'

cat(' '                                            , file = R.file, sep=c("\n")               )
cat('This is my stuff'                             , file = R.file, sep=c("\n"), append = TRUE)
cat('#'                                            , file = R.file, sep=c("\n"), append = TRUE)
cat(' '                                            , file = R.file, sep=c("\n"), append = TRUE)

my.df <- data.frame(scenario  = 3333,
                    AA        = 200,
                    BB        = 999,
                    CC        = 444,
                    DD        = 7)
str(my.df)

# Desired format in my_R_file.R
desired.format <- read.table(text = '
             scenario    AA    BB   CC  DD
                 3333   200   999  444   7
', header = TRUE, stringsAsFactors = FALSE)
str(desired.format)

# capture.output includes an unwanted row number
cat(' '                                            , file = R.file, sep=c("\n"), append = TRUE)
cat('capture.output'                               , file = R.file, sep=c("\n"), append = TRUE)
capture.output(my.df, file = R.file, append = TRUE)
cat(' '                                            , file = R.file, sep=c("\n"), append = TRUE)

# write.table returns an unwanted warning message
cat('write.table'                                  , file = R.file, sep=c("\n"), append = TRUE)
cat('my.df <- read.table(text = \''                , file = R.file, sep=c("\n"), append = TRUE)
write.table(my.df, file = R.file, col.names = TRUE, row.names = FALSE, quote = FALSE, append=TRUE)
cat('\', header = TRUE, stringsAsFactors = FALSE)' , file = R.file, sep=c("\n"), append = TRUE)
cat(' '                                            , file = R.file, sep=c("\n"), append = TRUE)

# sink does not return any useful output
#cat('sink'                                        , file = R.file, sep=c("\n"), append = TRUE)
#sink(R.file)
#sink()
#my.df
#sink()
#cat(' '                                           , file = R.file, sep=c("\n"), append = TRUE)

cat('This is the end'                              , file = R.file, sep=c("\n"), append = TRUE)
cat(' '                                            , file = R.file, sep=c("\n"), append = TRUE)

Here are the full contents of the recipient R file my_R_file.R:

This is my stuff
#
 
 
capture.output
  scenario  AA  BB  CC DD
1     3333 200 999 444  7
 
write.table
my.df <- read.table(text = '
scenario AA BB CC DD
3333 200 999 444 7
', header = TRUE, stringsAsFactors = FALSE)
 
This is the end

Here is the warning message returned by write.table:

Warning message:
In write.table(my.df, file = R.file, col.names = TRUE, row.names = FALSE,  :
  appending column names to file

Thank you for any suggestions on eliminating this warning message or arriving at a better solution. I would rather not suppress all warning messages.

CodePudding user response：

Notice that there is base:::print.data.frame method involved when evaluating my.df which is of class "data.frame". It has arguments such as row.names=. Accordingly you may specify:

capture.output(print(my.df, row.names=FALSE), file=R.file, append=TRUE)