Displaying 20 results from an estimated 6000 matches similar to: "help with knn from class library"
2008 Sep 19
3
How to do knn regression?
Hello,
I want to do regression or missing value imputation by knn. I searched
r-help mailing list. This question was asked in 2005. ksmooth and loess
were recommended. But my case is different. I have many predictors (p>20)
and I really want try knn with a given k. ksmooth and loess use band width to define
neighborhood size. This contrasts to knn's variable band width via fixing
a
2011 Sep 08
1
error in knn: too many ties in knn
Hello.
I found the behavior of knn(
http://stat.ethz.ch/R-manual/R-devel/library/class/html/knn.html) function
looking very strange.
Consider the toy example.
> library(class)
> train <- matrix(nrow=5000,ncol=2,data=rnorm(10000,0,1))
> test <- matrix(nrow=10,ncol=2,data=rnorm(20,0,1))
> cl <- rep(c(0,1),2500)
> knn(train,test,cl,1)
[1] 1 1 0 0 1 0 1 1 0 1
Levels: 0 1
It
2008 Oct 01
1
knn class probabilities
Good Day,
I'm using the knn function in the package class. With k set to 3,
the function returns proportions of 1/3, 0.5, 0.6, 2/3, 3/4, and 1.0
for the test cases. I don't understand how with k set to 3 the
proportions can be anything other than 1/3, 2/3, or 1.0 I've seen
similar inconsistencies with k set to 5.
R version 2.5.0 with redhat linux.
Thanks in advance.
Mike
2005 Jul 06
1
Error message NA/NaN/Inf in foreign function call (arg 6) when using knn()
I am trying to use knn to do a nearest neighbor classification. I tried using my dataset and got an error message so I used a simple example to try and understand what I was doing wrong and got the same message. Here is what I typed into R:
try
[,1] [,2] [,3] [,4]
r "A" "A" "T" "G"
r "A" "A" "T" "G"
f
2005 Mar 21
1
How to do knn regression
How can I do a simple k nearest neighbor regression in R? My training
data have 1 predictor and 1 outcome, both are numeric. I also need to
use FPE and SC to find the optimal model. I know there is knn() in
class package, but it's for knn classification. I also find a kknn
package. What function should I use?
Thanks in advance!
Menghui
2011 Aug 31
8
!!!function to do the knn!!!
hi, r users
i have a problem with KNN.
i have 2 datasets, X0 and X1.
>dim(X0)
>1471*13
dim(X1)
>5221*13
and for every instances in the dataset X1, i want to find the nearest
neighbour(1nn) in the dataset X0.
and i dont have the true classifications of dataset X1.
but the function knn() need true classifications(cl) to do prediction.
i just curious if there are some other function
2004 Feb 23
2
outputs of KNN prediction
Hello there:
I got 13 variables in my training/target set, the first 12 variables are
mixture of numerical and categorical variables. The last one is the one I
need
to predict, and it is a numerical variable.
>train<-read.table("train.txt")
>test<-read.table("test.txt")
>cl<-factor(train[,13])
>pred<-knn(train, test, clk=3, prob=TRUE)
>pred
I got
2006 Jun 07
1
knn - 10 fold cross validation
Hi,
I was trying to get the optimal 'k' for the knn. To do this I was using the following function :
knn.cvk <- function(datmat, cl, k = 2:9) {
datmatT <- (datmat)
cv.err <- cl.pred <- c()
for (i in k) {
newpre <- as.vector(knn.cv(datmatT, cl, k = i))
cl.pred <- cbind(cl.pred, newpre)
cv.err <- c(cv.err, sum(cl != newpre))
}
2010 Mar 09
1
create picture (k -the nearest neighbours)
Hi
I want to create a nice picture about my result of k -the nearest neighbours
algorithm. Here is my easy code:
#################################
library(klaR)
library(ipred)
library(mlbench)
data(PimaIndiansDiabetes2)
dane=na.omit(PimaIndiansDiabetes2)[,c(2,5,9)]
dane[,2]=log(dane[,2])
dane[,1:2]=scale(dane[,1:2])
zbior.uczacy=sample(1:nrow(dane),nrow(dane)/2,F)
2011 Aug 30
1
ROC plot for KNN
Hi I need some help with ploting the ROC for K-nearest neighbors. Since KNN
is a non-parametric classification methods, the predicted value will be
either 0 or 1.
It will not be able to test for different cutoff to plot ROC. What is the
package or functions I should use to plot ROC for KNN?
Thanks.
Qian
[[alternative HTML version deleted]]
2007 Apr 11
1
Function knn.dist from knnflex library
Hello,
I am feeling that this question can have a very simple answer, but I
can't find it.
I need to use the function knn.dist from knnflex library.
Whatever I try, I get the error:
Error in as.vector.dist(x, "character") : unused argument(s) ("character")
First example:
> a<-NULL
> a<-rbind(a,c(5.2,-8.1))
> a<-rbind(a,c(8.8,-16.1))
>
2008 Oct 29
1
Help with impute.knn
ear all,
This is my first time using this listserv and I am seeking help from the
expert. OK, here is my question, I am trying to use impute.knn function
in impute library and when I tested the sample code, I got the error as
followingt:
Here is the sample code:
library(impute)
data(khanmiss)
khan.expr <- khanmiss[-1, -(1:2)]
## ## First example
## if(exists(".Random.seed"))
2004 May 05
1
Segfault from knn.cv in class package (PR#6856)
The function knn.cv in the class package doesn't have error checking to
ensure that the length of the classlabel argument is equal to the number
of rows in the test set. If the classlabel is short, the result is often
a segfault.
> library(class)
> dat <- matrix(rnorm(1000), nrow=10)
> cl <- c(rep(1,5), rep(2,5))
> cl2 <- c(rep(1,5), rep(2,4))
> knn.cv(dat, cl)
[1] 2
2004 Feb 07
1
knn using custom distance metric
Hi,
There are two packages providing knn classification: class and knnTree.
However, it seems both uses Eucleadian distances only. How can I uses a
custom distance function with either package?
Thanks,
Xiao-Jun
2005 Oct 06
1
how to use tune.knn() for dataset with missing values
Hi Everybody,
i again have the problem in using tune.knn(), its giving an error saying
missing values are not allowed.... again here is the script for
BreastCancer Data,
library(e1071)
library(mda)
trdata<-data.frame(train,row.names=NULL)
attach(trdata)
xtr <- subset(trdata, select = -Class)
ytr <- Class
bestpara <-tune.knn(xtr,ytr, k = 1:25, tunecontrol = tune.control(sampling
2011 Mar 02
2
*** caught segfault *** when using impute.knn (impute package)
hi,
i am getting an error when calling the impute.knn
function (see the screenshot below).
what is the problem here and how can it be solved?
screenshot:
##################
*** caught segfault ***
address 0x513c7b84, cause 'memory not mapped'
Traceback:
1: .Fortran("knnimp", x, ximp = x, p, n, imiss = imiss, irmiss,
as.integer(k), double(p), double(n), integer(p),
2002 Feb 05
2
Measures of agreement
Greetings.
I've been experimenting with some algorithms for document classification
(specifically, a Naive Bayes classifier and a kNN classifier) and I would
now like to calculate some inter-rater reliability scores. I have the data
in a PostgreSQL database, such that for each document, each measure (there
are 9) has three variables: ap_(measure), nb_(measure), and
knn_(measure). ap is me
2005 Mar 15
1
KNN one factor predicting problem
Could anybody help me out please?
> cl<-as.factor(traindata[,13])
> knn(traindata[1:295,2], newdata[1:32,2], cl,k=2,
prob=TRUE)
Error in knn(traindata[1:295, 2], newdata[1:32, 2],
cl, k = m, prob = TRUE) :
Dims of test and train differ
Both traindata and newdata have 13 elements. Only one
of the first 12 elemnets is needed to predict the 13
element.
What's the problem of
2008 Aug 11
1
question about knn
Hello all,
am a newby in R,
am trying the knn function, and am doing just a stupid test :
> knn(c(1,2,3,4,5,6), c(3), k=4 ,prob=TRUE,factor(c(1:6)))
the result is unstable !! i have each time different result :
[1] 5
attr(,"prob")
[1] 0.1666667
Levels: 1 2 3 4 5 6
[1] 4
attr(,"prob")
[1] 0.1666667
Levels: 1 2 3 4 5 6
[1] 1
attr(,"prob")
[1] 0.1666667
Levels:
2004 Mar 29
1
Interpreting knn Results
Maybe you should show your colleague how to access help pages in R? Right
in ?knn, it says:
prob: If this is true, the proportion of the votes for the winning
class are returned as attribute 'prob'.
so 1.0 mean all three NNs are of the `winning'; i.e., predicted, class, and
0.66667 means 2 out of the 3 NNs are of the winning class, etc.
Andy
> From: Ko-Kang