Folks, I often build up R objects starting from NULL and then repeatedly using rbind() or cbind(). This yields code like:
a <- NULL for () { onerow <- craft one more row a <- rbind(a, onerow) } This works because rbind() and cbind() are forgiving when presented with a NULL arg: they act like nothing happened, and you get all.equal(x,rbind(NULL,x)) or all.equal(x,cbind(NULL,x)). This same idea is useful in building up a zoo matrix, by cbinding one column after another. I find this quite elegant, though I'm conscious that it leads to a lot of expensive memory management. This approach breaks around zoo because cbind(NULL,z) doesn't work: > tmp <- structure(c(2.65917577210146, 1.17190441781228, 0.838363890267146, -0.293979039853021, -0.132437820890186, 0.262002985990861, 2.16601367541420, 0.375245019370496, 0.0108451048014047, 1.56555812127923), index = structure(c(12509, 12510, 12513, 12514, 12515, 12516, 12521, 12524, 12528, 12529), class = "Date"), class = "zoo") > tmp 2004-04-01 2004-04-02 2004-04-05 2004-04-06 2004-04-07 2004-04-08 2.65917577 1.17190442 0.83836389 -0.29397904 -0.13243782 0.26200299 2004-04-13 2004-04-16 2004-04-20 2004-04-21 2.16601368 0.37524502 0.01084510 1.56555812 > cbind(NULL,tmp) 12509 12510 12513 12514 12515 12516 2.65917577 1.17190442 0.83836389 -0.29397904 -0.13243782 0.26200299 12521 12524 12528 12529 2.16601368 0.37524502 0.01084510 1.56555812 Warning message: In merge.zoo(..., all = all, fill = fill, suffixes = suffixes, retclass = "zoo") : Index vectors are of different classes: integer Date Is there an easy workaround; or am I deeply confused; is there a way out? :-) -- Ajay Shah http://www.mayin.org/ajayshah ajays...@mayin.org http://ajayshahblog.blogspot.com <*(:-? - wizard who doesn't know the answer. ______________________________________________ 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.