[R] How to get the threshold value for hierarchical clustering algorithms?

Dear R users, I am now working on the hierarchical clustering methods, and confused about the following problem. As you know, to form clustering from the hierarchical tree generated by the pairwise distance bw the elements, we have to set a threshold value to cut the tree horizonally such that

[R] How to calculate the derivative of matrix w.r.t another matrix?

Dear All I have a problem of calculating the derivative of dxm matrix A with respect to another dxm matrix B, where A= [a1 a2 ... am] and B =[b1 b2 ... bm] with ai and bj are vectors. Actually the matrix A itself is the first order derivative of a scalar J with respect to B, i.e., A = dJ/dB,

[R] How to compute the minimal distanct between a point and curve in N-dim space

Dear All, In the N-dimensional space, give a data point A and a curve f, how to write the explicit expression for calculating the minimal distance between A and f? Or have to use some nonlinear optimization method to calcualte it? Thanks for your point. Fred [[alternative HTML

[R] How to compute the minimal distanct between a point and curve in N-dim space

Dear All, In the N-dimensional space, give a data point A and a curve f, how to write the explicit expression for calculating the minimal distance between A and f? Or have to use some nonlinear optimization method to calcualte it? Thanks for your point. Fred [[alternative HTML version

[R] How to define a function to be smooth?

Hey, R-listers When we say a function f(t) is smooth, does this mean that f has infinite differentials with respect to t? Or any other formal definition on this? Thanks for your points. Fred [[alternative HTML version deleted]] __ [EMAIL

[R] What is the definition of curve continuity and smoothness

Dear R-listers, I am now using principal curves for data analysis. The definition of it required the accurate concept of curve continuity (C0, C1, ..., CK) and curve smoothness. So if anyone can introduce the exact definition of continuous for curves and what is the most popular textbooks for

[R] Is it possible to separate two independent components from arandom variable?

Hey, R-listers, Given the observed N random scalar variable x, with zero mean and unit variance, can we separate the two independent component x1 and x2 such that x = x1 + x2 (x1 and x2 are assumed to be zero mean)? Maybe there is no way to figure it out, and just wanna get some help and try it.

[R] How to get the pseudo left inverse of a singular square matrix?

Dear R-listers, I have a dxr matrix Z, where d r. And the product Z*Z' is a singular square matrix. The problem is how to get the left inverse U of this singular matrix Z*Z', such that U*(Z*Z') = I? Is there any to figure it out using matrix decomposition method? Thanks a lot for your help.

Re: [R] How to get the pseudo left inverse of a singular squarematrix?

Thank, Jerome The question is if this generalized inverse can make their product to be identity matrix? - Original Message - From: Jerome Asselin [EMAIL PROTECTED] To: Feng Zhang [EMAIL PROTECTED]; R-Help [EMAIL PROTECTED] Sent: Thursday, August 14, 2003 11:52 AM Subject: Re: [R] How

[R] A question on orthogonal basis vectors

Hey, R-listers, I have a question about determining the orthogonal basis vectors. In the d-dimensinonal space, if I already know the first r orthogonal basis vectors, should I be able to determine the remaining d-r orthognal basis vectors automatically? Or the answer is not unique? Thanks for

[R] How to plot a scatter-plot matrix?

Hey, R-listers I am going to plot a scatter-plot matrix using R. For example, give a matrix X=[x1, x2, ..., xn] where each xi is a column vector, how to plot all the pair scatter-plots between two different xi and xj? Is PAIRS able to achieve this function? Thanks for your help. Fred

[R] How to estimate 2-D principal curve using PCURVE?

Hey, R-listers I am a new user of R and just found the package of PCURVE which can estimate principal curve for arbitrary dimensional data set. Now I have some 2-Dimensional data set X, which is stored as an Nx2 matrix in data.txt file and looks as following: -1.5551 2.4183 1.0051 1.0102

[R] How to use PCURVE to estimate 2-D principal curves?

Hey, Rlisters. Does anybody know how to use the package PCURVE to estimate a 2-Dimensional principal curve? My 2-D data x is stored as a .txt file, looks as following: xx xx xx xx ... xx xx So how to write the command to get the principal curve? Thanks for your point. Fred

Re: [R] A dead problem on deriving the derivative equation.

Not for calculation on numbers, just to derive the symbolic formulation with theta, x.. - Original Message - From: Spencer Graves [EMAIL PROTECTED] To: Feng Zhang [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Sent: Thursday, March 27, 2003 6:08 PM Subject: Re: [R] A dead problem on deriving

[R] About statistical independece or cumulant books or papers

Hey I am now studying the statistical indepdence between arbitray two random variables. And want to use Cumulant or related method as the starting point. So anybody has some hints on providing me some good textbooks or papers on cumulant or statistical indepdence criteria? Thanks a lot. Fred

[R] How to draw several plots in one figure?

Hey, I want to draw several plots sequently, but have to make them dispaly in one figure. So how to achieve this? Thanks. Fred __ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help

Re: [R] How to draw several plots in one figure?

Thanks, Su. But I want to plot the several plots in the same x-y axis setting, not in multiple subplots. - Original Message - From: Steve Su [EMAIL PROTECTED] To: Feng Zhang [EMAIL PROTECTED] Sent: Wednesday, March 05, 2003 12:29 AM Subject: Re: [R] How to draw several plots in one figure

[R] How to estimate or approximate a 3-D surface

Hey, R-listers Now I am going to estimate or approximate a surface in 3-D space given a large enough number of (x,y,z) data sets. So for these 3-D data points, is it possible to get a surface function, like z=f(x,y) to represent this underlying surface? Thanks for your time and point. Fred

[R] How to determine the #,means and variances of 1-D Gaussian Mixture Model

Hey, R-listers I am going to approximate arbitrary 1-D data density by mixture of Gaussian models. The problem is that given a set of data generated from an unknown density function, and want to use a Gaussian mixture density model to approximate it. Now how to determine the number of components,

[R] How to generate multiple squre Orthogonal matrices?

Hey, all Will you please tell me how to generate multiple square orthogonal matrices for data transformation usage? Thanks. Fred __ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help

[R] How to calculate the closest distance from a point to a curve?

Hely, R-list Now I have non-parametric curve function, that is, I only use N 2-Dimensional data points to represent this curve, without explicit function formulation. And given a new measurement (x1,x)', how can I calculate the shortese Euclidean distance from this new data point to the above

[R] Urgent Help on Cumulant computation on two R.V's

Hey Now I am going to check the independence of random variables using cumulant function. So if R has such package or functions to calculate the sample cumulant of a random vector? Thanks a lot. Fred __ [EMAIL PROTECTED] mailing list

Re: [R] Covariance matrix for GMM

There is no way to answer this question? even for writing the sample covariance matrix formulation for the data set [X, Y] where X(n observations) and Y (m observations) are from the class 1 and class 2 which both are multidimensional normal distribution? - Original Message - From: Feng

Re: [R] Confused by SVD and Eigenvector Decomposition in PCA

Thanks for those replies. But I tested several cases, and found the two percentage from SVD and EVD are not the same. So how to explain the difference and which one should be the right one for use in PCA? - Original Message - From: antonio rodriguez [EMAIL PROTECTED] To: Feng Zhang

Re: [R] Confused by SVD and Eigenvector Decomposition in PCA

); %%Covariance matrix of ZeroedX [U,L] = eig(C); %% Eigen decompostion of C SE = diag(L); [0.89181.10981.2337]' SE(1)/sum(SE) 0.3813 This is the case that I was confused by. Fred - Original Message - From: Liaw, Andy [EMAIL PROTECTED] To: 'Feng Zhang' [EMAIL PROTECTED] Sent: Friday

[R] Confused by SVD and Eigenvector Decomposition in PCA

Hey, All In principal component analysis (PCA), we want to know how many percentage the first principal component explain the total variances among the data. Assume the data matrix X is zero-meaned, and I used the following procedures: C = covriance(X) %% calculate the covariance matrix;

[R] About STEM Plot in R

Hey Does anybody know if R can plot the 3-dimensinal stem graphs? In Matlab, there is such similare function to plot 3D plots, stem3(X,Y, Z), where X, Y , Z (column vectors) are coordinate values of data points. Thanks. Fred __ [EMAIL PROTECTED]

[R] Help on Scatte Plot Matrix

Hey, All Now I have a data set which is n-dimensional. And want to plot the Scatter Plot Matrix which is n by n. Does R have such function to achieve this? Thanks for your point. Fred __ [EMAIL PROTECTED] mailing list

[R] [R]Good advices or books on estimating the SPE?

Dear R'ers I am trying to use some distribution to test the hypothesis on my prediction error. Given a large numbe of sample data with unknown distribution, I first find some funtion to make regression. Now for each new data point, I can calculate the prediction error xi. So how to represent the