Gregory Ryslik wrote:
Why are they matrices? What is the additional dimension? And: what should become of the additional dimension? with 2d reference and prediction, do you want to produce 3d or 4d confusion "matrices"?Hi,Thank you for the help! Would this imply then that if my "answers" and "predicted" are both matrices, I need to first make them into factors? I was hoping to avoid that step...
Thank you again!
You are welcome. Claudia
Kind regards, Greg On Oct 8, 2010, at 10:04 AM, Claudia Beleites wrote:Gregory Ryslik wrote:Hi, I played with the table option but I seem to be only able to give me counts for numbers that exist. For example, if I don't have any 4's that are predicted, that number is skipped!Well, you need to tell the function that there _could_ be a 4 :ref <- factor (1 : 3) ref <- factor (1 : 4) pred <- factor (c (1 : 3, 1), levels = levels (ref)) ref[1] 1 2 3 4 Levels: 1 2 3 4pred[1] 1 2 3 1 Levels: 1 2 3 4table (ref, pred)pred ref 1 2 3 4 1 1 0 0 0 2 0 1 0 0 3 0 0 1 0 4 1 0 0 0 ClaudiaThanks, Greg Sent via BlackBerry by AT&T -----Original Message----- From: Claudia Beleites <cbelei...@units.it> Date: Fri, 08 Oct 2010 15:38:31 To: Gregory Ryslik<rsa...@comcast.net> Cc: R Help<r-help@r-project.org> Subject: Re: [R] confusion matrix Dear Greg, If it is only the NA that worries you: function table can deal with that. ? table and: example (table) If you want to make a confusion matrix that works also with fractional answers (e.g. 50% A, 50% B, a.k.a soft classification) then you can contact me and become test user of a package that I'm just writing (you can also wait until it is published to CRAN, but that will take a while). Best regards, Claudia Gregory Ryslik wrote:Hi Everyone, In follow up to my previous question, I wrote some code that correctly makes a confusion matrix as I need it. However, it only works when the numbers are between 1 and n. If the possible outcomes are between 0 and n, then I can't reference row "0" of the matrix and the code breaks. Does anyone have any easy fixes for this? I've attached the entire code to this email. As always, thank you for your help! Greg Code: answers<-matrix(c(4,2,1,3,2,1),nrow =6) mat1<- matrix(c(3,3,4,NA,4,2),nrow = 6) mat2<-matrix(c(3,2,1,4,2,3),nrow = 6) mat3<-matrix(c(4,2,2,2,1,1),nrow = 6) mat4<-matrix(c(4,2,1,3,1,4),nrow = 6) mat5<-matrix(c(2,3,1,4,2,3),nrow = 6) matrixlist<-list(mat1,mat2,mat3,mat4,mat5) predicted.values<- matrix(unlist(matrixlist),nrow = dim(mat1)[1]) confusion.matrix<-matrix(0, nrow =length(as.vector(unique(answers))),ncol = length(as.vector(unique(answers)))) for(i in 1:dim(predicted.values)[1]){ for(j in 1: dim(predicted.values)[2]){ predicted.value<- predicted.values[i,j] if(!is.na(predicted.value)){ true.value<- answers[i,] confusion.matrix[true.value, predicted.value] <- confusion.matrix[true.value,predicted.value]+1 } } } class.error<- diag(1- prop.table(confusion.matrix,1)) confusion.matrix<-cbind(confusion.matrix,class.error) confusion.data.frame<-as.data.frame(confusion.matrix)names(confusion.data.frame)[1:length(as.vector(unique(answers)))]<- 1:length(as.vector(unique(answers))) names(confusion.data.frame)[length(as.vector(unique(answers)))+1]<- "class.error" [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.orgmailing 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.-- Claudia Beleites Dipartimento dei Materiali e delle Risorse Naturali Università degli Studi di Trieste Via Alfonso Valerio 6/a I-34127 Triestephone: +39 0 40 5 58-37 68 email: cbelei...@units.it
-- Claudia Beleites Dipartimento dei Materiali e delle Risorse Naturali Università degli Studi di Trieste Via Alfonso Valerio 6/a I-34127 Trieste phone: +39 0 40 5 58-37 68 email: cbelei...@units.it ______________________________________________ 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.
