Steven Rytina wrote:
The rules for conformability of objects required for various operators
remain a mystery as do some related problems like the rules for recycling in
creating arrays etc. Would someone be able to direct me to where such rules are
stated?
In a related vein, there are all manner of operations that are readily coded in Gauss or in MATA that fail, often mysteriously, in R. Are there some guidelines available?
And here is a specific problem:
I would like to carry out logical comparisons between a (vector?) of
length EYE and each row of a JAY by EYE object, obtaining a conforming JAY by
EYE result of comparisons such as Obj[Jay,Eye] == Vec[Eye]
Any thoughts on how to effect this would be welcome.
Among many failed efforts,
as.matrix(7 element Vec) == { an 8 row, 7 column data.frame}
yields a 8 by 7 result
v1 vs Ob[1,1] v2 vs Obj[1,2] ...
v2 vs Ob[2,1] .
. et cetera
.
v7 vs Obj[7,1]
v1 vs Obj[8,1]
while
as.matrix(7 element Vec) == t{ the 8 row, 7 column data.frame} yields a
conformability error.
Thanks for any help or comments.
Not sure what the actual rule set (much less the rationale) is, but the
thing that seems to be happening is that
(a) comparisons and other operations between matrices require strict
conformance of dimensions. I.e. you cannot compare a 7x1 matrix to a 7x8
one.
(b) comparisons of data frames to vectors removes any dimension
attribute from the latter. So you can happily do
as.matrix(1:8,2,4)==as.data.frame(matrix(1:8,8,7)
but neither
as.matrix(1:7)==matrix(1:8,7,8)
nor
as.matrix(1:7)==matrix(1:8,8,7)
Transposing a data frame converts it to a matrix, so rule (a) kills you.
What you can do is either drop the as.matrix() stuff so that you compare
the transposed data frame to a vector, or (preferably) use a construct like
sweep(D, V, 2, "==")
--
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalga...@biostat.ku.dk) FAX: (+45) 35327907
______________________________________________
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.
