Appending text in write function [R]

Question

I am trying to append a line in an already existing .txt file. But my syntax overwrites this file :(

   fileConn <- file( "realization1.txt" )
      write(x =as.character(max(cumsum( rnorm( 10^7)))),
            file = fileConn,
            append = TRUE, sep = " ")


      write(x =as.character(max(cumsum( rnorm( 10^7)))),
            file = fileConn,
            append = TRUE, sep = " ")
   }

   close( fileConn )

Does anybody have any solution to this? Thanks for help!

possible duplicate of [Add lines to a file](http://stackoverflow.com/questions/7741575/add-lines-to-a-file) — Richard, Aug 16 '14 at 14:44
not ture. The answers here are different. Check @carl solution — Marcin, Aug 16 '14 at 19:52

score 5 · Accepted Answer · answered Aug 16 '14 at 16:55

I believe your difficulty comes from failing to open the file with the proper attributes set.

If you create the connection with fileConn <- file( "realization1.txt" ,open="a") , then all will work as you expect. Basically, so far as I can tell, write (which is a wrapper for cat ) cannot append unless the file connection was opened with "append" allowed.

score 2 · Answer 2 · answered Oct 01 '15 at 11:23

2

You can also use writeLines, which is about 20x faster than write. This makes a big difference if you are appending large character strings.

sink("outfile.txt", append = T)

x <- as.character(max(cumsum( rnorm( 10^7))))
writeLines(x)

sink()

answered Oct 01 '15 at 11:23

rafa.pereira

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And what about writeLines and write.table comparisons? – Marcin Oct 01 '15 at 15:07

score 0 · Answer 3 · answered Aug 16 '14 at 15:25

I would just use the command write.table

write.table(max(cumsum( rnorm( 10^7))),file="realization1.txt",append=TRUE,row.names=FALSE,col.names=FALSE)

write.table(max(cumsum( rnorm( 10^7))),file="realization1.txt",append=TRUE,row.names=FALSE,col.names=FALSE)

You will find the 2 values in the 'realizaion1.txt' file

Appending text in write function [R]

3 Answers3