Displaying 20 results from an estimated 2000 matches similar to: "Tutorials on R"
2007 Oct 04
5
combining vectors on unequal length
If I have two vectors
X<-1:10
Y<-1:5
When I combine them using cbind, the shorter one is repeated and both are made of the same length. Is there a methods that does this without duplicating the shorter one. I want to use this to store the data back to a file.
Thanks ../Murli
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2004 Nov 04
2
biplot drawing conc ellipses
Is there an option to draw concentration ellipses in biplots ? It seems
really nice to summarize large number of points of each group.
Cheers../ Murli
2007 Aug 07
5
small sample techniques
If my sample size is small is there a particular switch option that I need to use with t.test so that it calculates the t ratio correctly?
Here is a dummy example?
รก =0.05
Mean pain reduction for A =27; B =31 and SD are SDA=9 SDB=12
drgA.p<-rnorm(5,27,9);
drgB.p<-rnorm(5,31,12)
t.test(drgA.p,drgB.p) # what do I need to give as additional parameter here?
I can do it manually but
2007 Aug 01
5
t-distribution
If I have a calculated t can I get the probability associated with it
using an R function by giving it the df and t? I know I can do the whole
calculation using t.test() or get the t-distribution using qt(). If
t=1.11 and df =9 can I get the probability?
Thanks../Murli
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2007 Jun 26
3
inter-rater agreement index kappa
Is there a function that calculates the inter-rater agreement index
(kappa) in R?
Thanks ../Murli
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2009 Jul 14
4
Trig functions strange results
I am trying to calculate coordinate transformations and in the process of debugging my code using debug I found the following
Browse[1]> direction[i]
[1] -1.570796
Browse[1]> cos(direction[i])
[1] 6.123032e-17
Browse[1]> cos(-1.570796)
[1] 3.267949e-07
Browse[1]> direction[i]
[1] -1.570796
Browse[1]> cos(direction[i])
[1] 6.123032e-17
Browse[1]> cos(-1.570796)
[1] 3.267949e-07
2005 Feb 10
5
sample
I am trying to sample a subset from a matrix using sample.
The size of the matrix is 20X 1532. It works fine with this,
but when I transpose the matrix and try to sample it, it returns
null.
pick.set<-sample(tissue.exp.t,5,replace=FALSE,prob=NULL)
Is there something that I am missing here ?
Thanks ../Murli
2006 Jul 22
3
Multcomp
Here it is again, hope this is more clear
I am using the following data (only a small subset is given):
Habitat Fungus.yield
Birch 20.83829053
Birch 22.9718181
Birch 22.28216829
Birch 24.23136797
Birch 22.32147961
Birch 20.30783598
Oak 27.24047258
Oak 29.7730014
Oak 30.12608508
Oak 25.76088669
Oak 30.14750974
Hornbeam 17.05307949
Hornbeam 15.32805111
Hornbeam 18.26920177
Hornbeam 21.30987049
2006 Sep 06
2
biplot label size
Which is the parameter that is used to decrease the size of ylabs
plotted in biplot? I tried playing with cex and cex.lab I am not getting
it right
pc <- princomp(USArrests)
biplot(pc, xlabs = rep("", nrow(USArrests)),ylabs=(colnames(USArrests)))
Thanks../Murli
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2007 Mar 18
1
multcomp
I used the multcomp package sometime back for doing multiple
comparisons. I see that it has been updated and the methods like simint
are no longer supported. When I run the program it prompts to me to use
glht. How do I get the lower and upper conf int and the pValues using
glht? Does anyone have an example?
Thanks ../Murli
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2007 Jul 27
2
manipulating arrays
Can I insert an element in an array at a particular position without
destroying the already existing element?
X<-c(1,2,3,4,5)
I want to insert an element between 1 and 2.
Thanks ../Murli
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2009 Jul 24
2
computing the radius of an arc
Hi!!
I am interesting in computing the radius of an arc that best approximates a curve. Is there an R function that I can use to draw an arc?
Nothing useful came up when I searched help.search. Does anyone have any suggestion to do this?
Thanks ../Murli
2009 May 29
2
strsplit
I am trying split a string and use one part of it to label graphs. I am using strsplit for that. While I am able to split it, how do I access the separated parts.
> filName<-"chrI_2223"
>part<- strsplit(filName,"\\_")
> part
[[1]]
[1] "chrI" "2223"
> part[1]
[[1]]
[1] "chrI" "2223"
I looked up the help archive but did
2004 Nov 02
2
lda
Hi !!
I am trying to analyze some of my data using linear discriminant analysis.
I worked out the following example code in Venables and Ripley
It does not seem to be happy with it.
============================
library(MASS)
library(stats)
data(iris3)
ir<-rbind(iris3[,,1],iris3[,,2],iris3[,,3])
ir.species<-factor(c(rep("s",50),rep("c",50),rep("v",50)))
2006 Jul 24
2
running jobs in background
Can I run jobs in the background and the check the status of it from
time to time in Windows version of R?
Thanks ../Murli
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2008 Mar 02
2
listing components of an object
Is there a method to list the components of an object, instead of looking at the help for that method? Let me be more clear with an example
data(iris)
## tune `svm' for classification with RBF-kernel (default in svm),
## using one split for training/validation set
obj <- tune(svm, Species~., data = iris,
ranges = list(gamma = 2^(-1:1), cost = 2^(2:4)),
2006 Sep 01
3
histograms
I am interested in plotting histograms for the following data
Isoform
Tumor_65_198
Tumor_50_192
Tumor_80_167
Tumor_80_204
Tumor_95_197
Tumor_70_189
Tumor_90_202
Tumor_40_177
Tumor_60_21
Tumor_70_174
Tumor_70_147
Tumor_50_5
ABCC4-2007
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ABCC4-2008
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ABCC4-2009
0
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ABCC4-2010
2008 Jun 25
1
stringdot
Hi!!
I am trying to figure out how to use the string kernel "stringdot" in kernlab.
k <- function(x,y) {
(sum(x*y) +1)*exp(-0.001*sum((x-y)^2))
}
class(k) <- "kernel"
data(promotergene)
## train svm using custom kernel
gene.k <- ksvm(Class~.,data=promotergene,kernel=k,C=10,cross=5) # works fine in this case
gene.rbf <-
2004 Oct 01
1
hier.part
I am using the hier.part package for calculating the goodness of fit.
Before I started with
my data I tried to use the example that the package comes with . I have
loaded the library
hier.part and gtools. But the package gives the following error
Loading required package: gregmisc
Loading required package: gregmisc
Warning messages:
1: There is no package called 'gregmisc' in:
2005 Feb 11
1
Random Matrix theory
Any package that implements Random matrix theory application in R.
I am completely new to this subject, so just wanted to explore it.
Cheers ../Murli