write.table() append argument

Question

When i run the following code the csv file has the 'DF' data frame followed by an 'x' on the next row then 'notes' on the row after.

Why is it outputting the 'x' and is there a way to stop it doing that? I want just the data frame followed by 'notes'.

DF <- data.frame(numbers=1:3, letters=c("a","b","c"))
write.table(DF, file="filename.csv", sep=",", row.names=FALSE)

write.table( "notes", file="filename.csv", append=TRUE, sep=",", 
row.names=FALSE)

output:

numbers letters
1       a
2       b
3       c
x
notes

Answer 1

The documentation of write.table says this:

x: the object to be written, preferably a matrix or data frame. If not, it is attempted to coerce x to a data frame.

Since you don't pass a data.frame, this happens internally:

x <- "notes"; x <- data.frame(x)

This creates the x as a column name:

print(x)
      x
1 notes

You can set col.names = FALSE to prevent writing it to the file.