Re: [R] plot rows of matrix against a vector on one graph

2007-09-26 Thread Wiebke Timm
On 26.09.2007, at 13:46, Olena Morozova wrote: > I am very new to R and statistical analysis in general. I am trying > to plot > a matrix of several hundred rows against a vector of 4 values. This > all has > to be on the same graph with different rows represented by > different color. > Thi

Re: [R] finding a stable cluster for kmeans

2007-09-26 Thread Wiebke Timm
On 26.09.2007, at 09:54, Prof Brian Ripley wrote: > On Wed, 26 Sep 2007, Friedrich Leisch wrote: > >>>>>>> On Tue, 25 Sep 2007 20:16:05 -0400, >>>>>>> Wiebke Timm (WT) wrote: >> >> > You might want to check if there is a neural

Re: [R] finding a stable cluster for kmeans

2007-09-25 Thread Wiebke Timm
You might want to check if there is a neural gas algorithm in R. kmeans generally has a high variance since it is very dependent on the initialization. Neural gas overcomes this problem by using a ranked list of neighbouring data points instead using data points directly. It is more stable (

Re: [R] Strange behaviour of lars method

2007-09-20 Thread Wiebke Timm
Thanks for your answer! On 20.09.2007, at 12:48, Tim Hesterberg wrote: > Might you be having numerical problems? That might very well be what's happening. Did hope that it only happens late in the procedure so I can ignore it, but those Cp values indicate I maybe can't. > If you're using th

[R] Problem with lars

2007-09-20 Thread Wiebke Timm
Hi! Ok, probably my last mail was too long. Questions are: * Did someone try lars on data with much more components than data points? Did you observe bad overfitting, too? Any other observations? * Why might the lars (least angle regression from lars package) method produce beta values that

Re: [R] Comprehensive New Learning Resource for R

2007-09-20 Thread Wiebke Timm
On 20.09.2007, at 09:24, Rob Kabacoff wrote: > I hope that you find this useful. Please feel free to link to the > site. Very nicely done from what I saw by browsing the site a little. Good colors, good content, easy to navigate. Thanks! You might want to add self-organizing maps as a cross-

[R] Strange behaviour of lars method

2007-09-19 Thread Wiebke Timm
Hi! When I apply the lars (least-angle-regression) method to my data (3655 features, only 355 data points, no I did not mistype), I observe a strange behaviour: 1) The beta values tend to grow into real high values quite fast up to a point where they overflow and get negative. The overflow