From: David Afshartous <dafshartous_at_med.miami.edu>

Date: Tue, 08 Jul 2008 16:56:55 -0400

*> aggregate(dat[c(3,4)], dat[c(1,2)], sd)
*

Error in var(x, na.rm = na.rm) : missing observations in cov/cor

*> aggregate(dat[c(3,4)], dat[c(1,2)], sd, na.rm = TRUE)
*

Error in var(x, na.rm = na.rm) : no complete element pairs

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 08 Jul 2008 - 20:54:55 GMT

Date: Tue, 08 Jul 2008 16:56:55 -0400

All,

I've been using aggregate() to compute means and standard deviations at time/treatment combinations for a longitudinal dataset, using na.rm = TRUE for missing data.

This was working fine before, but now when I re-run some old code it isn't. I've backtracked my steps and can't seem to find out why it was working before but not now. In any event, below is a reproducible example of the current problem, viz., calculating the standard deviation via aggregate and employing na.rm = TRUE is not working.

Thanks,

David

dat = data.frame( Hour = c(0, 0, 0, 0, 1, 1,1, 1), Drug = factor(c("P", "D", "P", "D", "P", "D", "P", "D")), Y1 = rnorm(8, 0), Y2 = c(NA, NA, NA, NA, 1, 2, 3, 4) )

*> aggregate(dat[c(3,4)], dat[c(1,2)], mean)
*

Hour Drug Y1 Y2

1 0 D -0.75534554 NA 2 1 D 0.27529835 3 3 0 P -0.03949923 NA 4 1 P 0.02627489 2

Error in var(x, na.rm = na.rm) : missing observations in cov/cor

Error in var(x, na.rm = na.rm) : no complete element pairs

*> sessionInfo()
*

R version 2.7.1 (2008-06-23)

i386-apple-darwin8.10.1

locale:

en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8

attached base packages:

[1] stats graphics grDevices utils datasets methods base

loaded via a namespace (and not attached):
[1] grid_2.7.1 lattice_0.17-8 nlme_3.1-89

*>
*

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