Displaying 20 results from an estimated 500 matches similar to: "Minimizing mahalanobis distance to negative orthant"
2006 Apr 29
1
SSPIR problem
I am having a problem with the package SSPIR. The code below
illustrates it. I keep getting the message: "Error in y - f :
non-conformable arrays."
I tried to tweak the code below in many different ways, for example,
substituting rbind for cbind, and sometimes I get a different error
message, but I could not find a variation of this code that would
work.
Any help will be greatly
2010 Jul 16
1
Nested if help
Hello,
I am trying to find a direct way to write a nested if of sorts to find data
for a specific time range for a specific day (across a range of days) and
have exhausted my abilities with the manuals I have at hand. I have a good
deal of data of this approximate form:
day time price
1 1am 5
1 2am 7
1 3am 9
1 4am 12
2 1am 5
2 2am 7
2
2017 Jun 16
2
Varios gráficos en una vista en OpenAir
Funciona perfecto!
Gracias Carlos.
Atte.
Novvier Uscuchagua
De: Carlos Ortega [mailto:cof en qualityexcellence.es]
Enviado el: viernes, 16 de junio de 2017 13:46
Para: Novvier Marco Uscuchagua Cornelio <novvier en outlook.com.pe>
CC: r-help-es en r-project.org
Asunto: Re: Varios gráficos en una vista en OpenAir
Hola,
Prueba entonces esto, que sí que funciona...
#-----------------------
2012 Aug 07
1
lm with a single X and step with several Xi-s, beta coef. quite different:
Hi, (R version 2.15.0)
I am running a pgm with 1 response (earlier standardized Y) and 44
independent vars (Xi) from the same data =a2:
When I run the 'lm' function on single Xi at a time, the beta
coefficient for let's say X1 is = -0.08 (se=0.03256)
But when I run the same Y with 44 Xi-s with the 'step' function (because
I left direction parameter empty, I assume a backward
2006 Aug 03
1
geodesic distance
Hi,
has anyone ever seen implemented in R the following "geodesic"
distance between positive definite pxp matrices A and B?
d(A,B) = \sum_{i=1}^p (\log \lambda_i)^2
were \lambda is the solution of det(A -\lambda B) = 0
thanks
stefano
2009 Jul 20
2
mahalanobis distance
http://www.nabble.com/file/p24569511/mahalanobis.txt mahalanobis.txt
http://www.nabble.com/file/p24569511/concentrations.txt concentrations.txt
Dear Forum members,
I have a problem calculating mahalanobis distances. My data file
mahalanobis.txt and categories file concentrations.txt are attached. I do
the following steps:
x <- as.matrix(read.table("mahalanobis.txt", header=TRUE))
2017 Jun 16
2
Varios gráficos en una vista en OpenAir
Hola Carlos,
Me parece que timePlot genera los gráficos en un formato diferente.
Al ejecutar grid.arrange genera el siguiente error:
Error in gList(list(list(plot = list(formula = value ~ date | default, :
only 'grobs' allowed in "gList"
Gracias.
Atte.
Novvier Uscuchagua
De: Carlos Ortega [mailto:cof en qualityexcellence.es]
Enviado el: viernes, 16 de junio de 2017 12:38
2004 Mar 26
1
Mahalanobis
Dear all
Why isn'it possible to calculate Mahalanobis distances with R for a matrix
with 1 row (observations) more than the number of columns (variables)?
> mydata <- matrix(runif(12,-5,5), 4, 3)
> mahalanobis(x=mydata, center=apply(mydata,2,mean), cov=var(mydata))
[1] 2.25 2.25 2.25 2.25
> mydata <- matrix(runif(420,-5,5), 21, 20)
> mahalanobis(x=mydata,
2004 Sep 12
2
mahalanobis distance
Is there a function that calculate the mahalanobis distance in R .
The dist function calculates "euclidean"', '"maximum"', '"manhattan"',
'"canberra"',
'"binary"' or '"minkowski"'.
Thanks ../Murli
2010 Jun 22
1
Mahalanobis distance
I am a new R user. i have a question about Mahalanobis distance.actually i have 300 rows and 7 columns. columns are different measurements, 300 rows are genes. since genes can
classify into 4 categories. i used dist() with euclidean distance and cmdscale to do MDS plot. but find out Mahalanobis distance may be
better. how do i use Mahalanobis() to generate similar dist object which i can use
2005 Dec 14
1
About help on 'mahalanobis'
Hi,
help on 'mahalanobis' (in the stats package in Rv2.2.0) now says:
"Description:
Returns the Mahalanobis distance of all rows in 'x' and the vector
mu='center' with respect to Sigma='cov'. This is (for vector 'x')
defined as
D^2 = (x - mu)' Sigma^{-1} (x - mu)"
It does return D^2 as written. However,
2005 Jun 24
1
Mahalanobis distances
Dear R community
Have just recently got back into R after a long break and have been amazed at
how much it has grown, and how active the list is! Thank you so much to all
those who contribute to this amazing project.
My question:
I am trying to calculate Mahalanobis distances for a matrix called "fgmatrix"
>dim(fgmatrix)
[1] 76 15
>fg.cov <- cov.wt(fgmatrix)
2008 Dec 08
1
Clustering with Mahalanobis Distance
Dear R ExpeRts,
I'm having memory difficulties using mahalanobis distance to trying to cluster in R. I was wondering if anyone has done it with a matrix of 6525x17 (or something similar to that size). I have a matrix of 6525 genes and 17 samples. I have my R memory increased to the max and am still getting "cannot allocate vector of size" errors. My matrix "x" is
2009 Oct 23
1
reference for mahalanobis {stats}
The help on mahalanobis {stats} does not include any reference. I'm
interested in understand why Mahalanobis is defined in its current way
and how to use it. Could somebody point me a good book on this? I have
looked through a few books, but they all give very light explanation
on it.
2004 Jan 21
1
outlier identification: is there a redundancy-invariant substitution for mahalanobis distances?
Dear R-experts,
Searching the help archives I found a recommendation to do multivariate
outlier identification by mahalanobis distances based on a robustly estimated
covariance matrix and compare the resulting distances to a chi^2-distribution
with p (number of your variables) degrees of freedom. I understand that
compared to euclidean distances this has the advantage of being scale-invariant.
2010 Mar 03
1
cluster with mahalanobis distance
How can I perform cluster analysis using the mahalanobis distance instead of
the euclidean distance?
thank you
Naama Wolf
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View this message in context: http://n4.nabble.com/cluster-with-mahalanobis-distance-tp1577038p1577038.html
Sent from the R help mailing list archive at Nabble.com.
2012 May 30
1
cluster with mahalanobis distance
How can I perform cluster analysis using the mahalanobis distance instead of
the euclidean distance?
Thank you
Maria Froes
[[alternative HTML version deleted]]
2008 Oct 07
1
vectorization of a loop for mahalanobis distance calculation
Dear all,
We have a data frame x with n people as rows and k variables as columns.
Now, for each person (i.e., each row) we want to calculate a distance
between him/her and EACH other person in x. In other words, we want to
create a n x n matrix with distances (with zeros in the diagonal).
However, we do not want to calculate Euclidian distances. We want to calculate
Mahalanobis distances, which
2007 Feb 20
1
Mahalanobis distance and probability of group membership using Hotelling's T2 distribution
I want to calculate the probability that a group will include a particular
point using the squared Mahalanobis distance to the centroid. I understand
that the squared Mahalanobis distance is distributed as chi-squared but that
for a small number of random samples from a multivariate normal population
the Hotellings T2 (T squared) distribution should be used.
I cannot find a function for
2011 Sep 26
2
Mahalanobis Distance
Hello R helpers,
I'm trying to use Mahalanobis distance to calculate distance of two time
series, to make some comparations with euclidean distance, DTW, etc, but I'm
having some dificults.
I have, for example, two objects:
s.1 <- c( 5.6324702, 1.3994353, -3.2572327, -3.8311846, -1.2248719,
0.9894694, -2.2835332, -5.1969285, -5.2823988, -3.1499400, -1.7307950,
2.8221209,