correlations between columns for each row

Error in cor(x[a], x[b], use = "complete.obs") : 'x' must be numeric

This is strange, it works on your example (and you've understood what I'm trying to do perfectly), but then when I use it on the original data it comes up with the error above
I've checked str() and the columns are all numeric

???

-----Original Message----- From: Joshua Wiley
Sent: Tuesday, November 15, 2011 7:14 PM
To: robgriffin247
Cc: r-help at r-project.org
Subject: Re: [R] correlations between columns for each row

Hi Rob,

Here is one approach:


## define a function that does the calculations
## (the covariance of two vectors divided by the square root of
## the products of their variances is just a correlation)
rF <- function(x, a, b) cor(x[a], x[b], use = "complete.obs")

set.seed(1)
bigdata <- matrix(rnorm(271 * 13890), ncol = 271)

results <- apply(bigdata, 1, FUN = rF, a = 174:213, b = 214:253)

## combine
bigdata <- cbind(bigdata, iecorr = results)

Hope this helps,

Josh

On Tue, Nov 15, 2011 at 8:42 AM, robgriffin247
<robgriffin247 at hotmail.com> wrote:

Just as an update on this problem:
I have managed to get the variance for the selected columns

Now all I need is the covariance between these 2 selections -
the two target columns are and the aim is that a new column contain a
covariance value between these on each row:

maindata[,c(174:213)] and maindata[,c(214:253]

I've played around with all sorts of apply (and derivatives of apply) and in
various different setups so I think I'm close but I feel like I'm chasing my
tail here!

--
View this message in context: http://r.789695.n4.nabble.com/correlations-between-columns-for-each-row-tp4039193p4073208.html
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-- 
Joshua Wiley
Ph.D. Student, Health Psychology
Programmer Analyst II, ATS Statistical Consulting Group
University of California, Los Angeles
https://joshuawiley.com/