Hello All. I must be missing the really obvious here: mm <- function(d, i) median(d[i]) b1 <- boot(gravity$g, mm, R = 1000) b1 b2 <- boot(gravity$g, mm, R = 1000, strata = gravity$series) b2
Both b1 and b2 seem to have done (almost) the same thing, but it looks like the strata argument in b2 has been ignored. However, str(b1) vs str(b2) does show that the strata have been noted correctly. But b2$t is a 1000 x 1 array, not a 1000 x 8 array (gravity$series is a factor with 8 levels). There is a more complex example in ?boot using the same data set that gives a result that seems to make sense (2 levels in the factor, so $t has 2 columns). I either misunderstand the expected behavior or I've missed some punctuation or syntax detail. TIA, Bryan ************* Bryan Hanson Acting Chair Professor of Chemistry & Biochemistry DePauw University, Greencastle IN USA > sessionInfo() R version 2.11.0 (2010-04-22) x86_64-apple-darwin9.8.0 locale: [1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8 attached base packages: [1] datasets tools grid graphics grDevices utils stats [8] methods base other attached packages: [1] boot_1.2-42 brew_1.0-3 faraway_1.0.4 [4] GGally_0.2 xtable_1.5-6 mvbutils_2.5.1 [7] ggplot2_0.8.7 digest_0.4.2 reshape_0.8.3 [10] proto_0.3-8 ChemoSpec_1.43 R.utils_1.4.0 [13] R.oo_1.7.2 R.methodsS3_1.2.0 rgl_0.91 [16] lattice_0.18-5 mvoutlier_1.4 plyr_0.1.9 [19] RColorBrewer_1.0-2 chemometrics_0.8 som_0.3-5 [22] robustbase_0.5-0-1 rpart_3.1-46 pls_2.1-0 [25] pcaPP_1.8-1 mvtnorm_0.9-9 nnet_7.3-1 [28] mclust_3.4.4 MASS_7.3-5 lars_0.9-7 [31] e1071_1.5-23 class_7.3-2 ______________________________________________ R-help@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.
