[R] Adding new columns to (output) data - e.g., read 5 cols write 8

[Erik Iverson]

Esmail -

Esmail Bonakdarian wrote:
> Hello, I have the following task I'd like to accomplish:
> 
> A file contains 5 columns of data (several hundred rows), let's call
> them a, b, c, d and e (ie these are their column headers)

Are these 5 vectors of data stored in a data.frame?  I assume so.

> 
> I also have a set of definitions, e.g.,
> 
> f = a + b
> g = a * 3
> h = c + d
> etc.
> 
> I would like to write out a new .rda file that contains columns
> 
> a b c d e f g h etc.
> 
> I.e. , the original data plus new columns (with headers and data).

Example,

test <- data.frame(a = 1:10, b = 2:11, c = 3:12)
test2 <- transform(test, d = 2*a + b, e = 3*c)
save(test2, file = "test2.Rdata")

Does this help?

Best,
Erik Iverson