I think there may be some confusion here. ************************ 4) x which is a 844x7 matrix having value "Good", "Moderate", etc.
Correct. ********************************** To be clear: x is a matrix of **integers** (presumably population counts) with 7 columns with names "Good", "Moderate", ... etc. Apologies if this was already clear from the above. -- Bert On Fri, Jan 24, 2025 at 11:14 AM Duncan Murdoch <murdoch.dun...@gmail.com> wrote: > I'll answer your question inline. > > On 2025-01-24 2:03 p.m., Sorkin, John wrote: > > I ran the following code: > > marginalcats <- aggregate(meanbyCensusIDAndDay3$cats, > > list(meanbyCensusIDAndDay3$CensusID),table) > > followed by > > str(marginalcats) > > > > I received the following output: > > 'data.frame': 844 obs. of 2 variables: > > $ Group.1: num 6e+09 6e+09 6e+09 6e+09 6e+09 ... > > $ x : int [1:844, 1:7] 14 14 14 14 14 14 14 14 14 14 ... > > ..- attr(*, "dimnames")=List of 2 > > .. ..$ : NULL > > .. ..$ : chr [1:7] "Good" "Moderate" "Unhealthy For Some" "Unhealthy" > ... > > > > I am trying to understand the output. I believe it says that marginalcats > > (1) is a data frame > > (2) the df has two elements (I) Group.1 and (II) x > > Correct so far. > > > (3) Group.1 is a ?list? of number > > No, it's a numeric vector. The length doesn't print because it's in a > dataframe, so the length is 844, the number of dataframe observations. > > > > (4) x which is a 844x7 matrix having value "Good", "Moderate", etc. > > Correct. > > > > > A few questions: > > (A) Is the interpretation given above correct? > > (B) Does the .. ..$ : NULL mean that the matrix has no row names? > > Yes. > > > (C) What does "attr(*, "dimnames")=List of 2" mean? > > That says x has an attribute called "dimnames", which is a list with two > elements. They are the row names (which is NULL, you don't have any) > and the column names. > > > (D) Does it mean that the dimensions of the matrix are stored as two > separate lists? > > No. The dim is an attribute which is shown implicitly as "[1:844, > 1:7]", i.e. c(844, 7). > > Duncan Murdoch > > > (E) If so, how do I access the lists? > > When I enter > > dimnames(marginalcatsx$x) > > I receive: > > > > [[1]] > > NULL > > > > [[2]] > > [1] "Good" "Moderate" "Unhealthy For Some" > "Unhealthy" "Very Unhealthy" "Hazardous1" > > [7] "Hazardous2" > > > > Thank you, > > John > > > > John David Sorkin M.D., Ph.D. > > Professor of Medicine, University of Maryland School of Medicine; > > Associate Director for Biostatistics and Informatics, Baltimore VA > Medical Center Geriatrics Research, Education, and Clinical Center; > > PI Biostatistics and Informatics Core, University of Maryland School of > Medicine Claude D. Pepper Older Americans Independence Center; > > Senior Statistician University of Maryland Center for Vascular Research; > > > > Division of Gerontology and Paliative Care, > > 10 North Greene Street > > GRECC (BT/18/GR) > > Baltimore, MD 21201-1524 > > Cell phone 443-418-5382 > > > > > > > > ______________________________________________ > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > https://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > https://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide https://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
