Question

I’ve got a headerfile with exactly 4 rows in a fixed width format (saved with the write.matrix function from the MASS package).

Now I want to create a new Matrix with the headerfile I created above. Is it possible in R to add a fixed multiline header (e.g. as “text”) to a matrix?

An example: I’ve got a header like

AB
CDEF 123456
GHIJK 789     101112
LMNOP

And then I want to create a matrix with date in first column and then the data (from another file) in the second column like

892201 0.1
892202 0.8

and so on. Note: It has to be the described format, because the program just read the fixed width format explained above.

Answer 1

You can write the second set of data into the existing file using the write.table() function with the append = TRUE argument.

If I have file foo.txt with the header you show, then I can add some dates and other data to that file by first creating the data object I want to append:

dat <- data.frame(dates = Sys.Date() + 0:4, data = seq(0.1, 0.5, by = 0.1))

> dat
       dates data
1 2012-06-12  0.1
2 2012-06-13  0.2
3 2012-06-14  0.3
4 2012-06-15  0.4
5 2012-06-16  0.5

The the following will append dat without any extraneous headers or row names on to the existing header file

write.table(dat, "foo.txt", append = TRUE, col.names = FALSE, row.names = FALSE)

foo.txt now looks like this:

$ cat foo.txt
AB
CDEF 123456
GHIJK 789     101112
LMNOP
2012-06-12 0.1
2012-06-13 0.2
2012-06-14 0.3
2012-06-15 0.4
2012-06-16 0.5