Message-ID: <CAEd7G2eTOoB0DtNUtWi4ZKqPFwJAGB6gJ_WDjH9FB1=Y9eZ+wg@mail.gmail.com>
Date: 2013-03-13T21:43:29Z
From: Pedro Mardones
Subject: calculating column difference in a matrix
Dear R users;
Consider the following toy example:
a <- matrix(c(2,3,4,NA,NA,5,8,NA,8,NA), 5, 2)
b <- cbind(a,apply(a, 1, diff, na.rm = TRUE))
What I would like be able to get is:
c <- matrix(c(2,3,4,NA,NA,5,8,NA,8,NA,3,5,-4,8,NA), 5, 3)
i.e., for each row if both values (column 1 and 2) are NA then the
difference must return NA, but if any of those two values is different
from NA (!is.na), I would like to actually perform the difference
(something like assigning 0 instead to NA to the cell).
I'd appreciate any hint or comment
Best,
Pedro
BTW: the reason of this is that I'm trying to build an error checking
procedure for a big dataset I have