[R] subtract 2 columns in a data.frame

Ko-Kang Kevin Wang kwan022 at stat.auckland.ac.nz
Thu Sep 4 13:50:55 CEST 2003

On 4 Sep 2003, Ulrich Leopold wrote:

> could someone point me to the right command to subtract 2 columns in a
> data.frame. Might be a bit embarrassing question. But I cannot figure
> out how to do this simple command in R.

Suppose your data frame is called foo, and you want the first column minus 
the second:
  foo[,1] - foo[,2]



"On two occasions, I have been asked [by members of Parliament],
'Pray, Mr. Babbage, if you put into the machine wrong figures, will
the right answers come out?' I am not able to rightly apprehend the
kind of confusion of ideas that could provoke such a question."

-- Charles Babbage (1791-1871) 
---- From Computer Stupidities: http://rinkworks.com/stupid/

Ko-Kang Kevin Wang
Master of Science (MSc) Student
SLC Tutor and Lab Demonstrator
Department of Statistics
University of Auckland
New Zealand
Homepage: http://www.stat.auckland.ac.nz/~kwan022
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