similar to: operating on arrays of unknown dimensionality

Displaying 20 results from an estimated 8000 matches similar to: "operating on arrays of unknown dimensionality"

2009 Jul 21
1
subscript into matrix discards row/column names
Dear R-help, When the result of a matrix subscription degenerates to a scalar the names implied by the dimnames are discarded. > x <- matrix(0, 1, 1, dimnames=list('a', 'x')) ## below I expected result to have names='x', it's not > x[1,] [1] 0 ## below I expected result to have names='a', it's not > x[,1] [1] 0 This is probably a side effect
2004 Nov 24
2
LDA with previous PCA for dimensionality reduction
Dear all, not really a R question but: If I want to check for the classification accuracy of a LDA with previous PCA for dimensionality reduction by means of the LOOCV method: Is it ok to do the PCA on the WHOLE dataset ONCE and then run the LDA with the CV option set to TRUE (runs LOOCV) -- OR-- do I need - to compute for each 'test-bag' (the n-1 observations) a PCA
2010 Mar 01
0
Is package "dr" appropriate for reducing the dimensionality of molecules conformational space ?
I anticipate lacking of prior experience with dimensionality reduction problems. Some scientists concerned with drug discovery performed several steered Molecular Dynamics simulations of the alanine-dipeptide molecule dragged by a radial force from an equilibrium conformation to another different equilibrium conformation. They sampled at regular intervals 7 dihedral angles, 5 bending angles, and
2018 Jul 07
2
Testing for vectors
On Sat, Jul 7, 2018 at 12:54 PM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote: > On 07/07/2018 1:20 PM, Hadley Wickham wrote: >> >> Hi all, >> >> Is there are base function that I've missed that tests if an object is >> a vector in the dimensionality sense, rather than the data structure >> sense? i.e. something that checks is.null(dim(x)) ?
2005 May 08
3
Light-weight data.frame class: was: how to add method to .Primitive function
Hi, Encouraged by a tip from Simon Urbanek I tried to use the S3 machinery to write a faster version of the data.frame class. This quickly hits a snag: the "[.default"(x, i) for some reason cares about the dimensionality of x. In the end there is a full transcript of my R session. It includes the motivation for writing the class and the problems I have encountered. As a result I see
2010 Feb 14
1
Dimensional reduction package
Is there any R package which implements non-linear dimensionality reduction (LLE, ISOMAP, GTM, and so on) and/or intrinsic dimensionality estimation ? Thank you, Maura tutti i telefonini TIM! [[alternative HTML version deleted]]
2008 Jul 23
2
shQuote and cat
Dear R-users, It is my understanding that cat(shQuote(a.string)) should print the origintal a.string. Is this right? I am not sure cat() correctly prints strings which are generated by triple-shQuote(): > shQuote(shQuote("a")) [1] "\"\\\"a\\\"\"" > cat(shQuote(shQuote(shQuote("a"))), '\n')
2008 Jul 23
2
shQuote and cat
Dear R-users, It is my understanding that cat(shQuote(a.string)) should print the origintal a.string. Is this right? I am not sure cat() correctly prints strings which are generated by triple-shQuote(): > shQuote(shQuote("a")) [1] "\"\\\"a\\\"\"" > cat(shQuote(shQuote(shQuote("a"))), '\n')
2010 Jun 26
3
converting result of substitute to 'ordidnary' expression
Dear R users, As substitute() help page points out: Substituting and quoting often causes confusion when the argument is 'expression(...)'. The result is a call to the 'expression' constructor function and needs to be evaluated with 'eval' to give the actual expression object. And indeed I am confused. Consider: > dat <- data.frame(x=1:10,
2010 Jun 26
3
converting result of substitute to 'ordidnary' expression
Dear R users, As substitute() help page points out: Substituting and quoting often causes confusion when the argument is 'expression(...)'. The result is a call to the 'expression' constructor function and needs to be evaluated with 'eval' to give the actual expression object. And indeed I am confused. Consider: > dat <- data.frame(x=1:10,
2010 Jun 26
2
subset arg in subset(). was: converting result of substitute to 'ordidnary' expression
Dear R users, Please disregard my previous post "converting result of substitute to 'ordidnary' expression". The problem I have has nothing to do with substitute. Consider: > dat <- data.frame(x=1:10, y=1:10) > subsetexp <- expression(5<x) > ## this does work > subset(dat, eval(subsetexp)) x y 6 6 6 7 7 7 8 8 8 9 9 9 10 10 10 > ##
2010 Feb 19
0
"tsne" package for t-SNE dimensionality reduction
I'd like to announce the availability of the "tsne" package. It provides the T distributed Stocastic Neighbor Embedding algorithm by van der Maaten and Hinton: 1. http://ict.ewi.tudelft.nl/~lvandermaaten/t-SNE.html 2. L.J.P. van der Maaten and G.E. Hinton. Visualizing High-Dimensional Data Using t-SNE. Journal of Machine Learning Research 9(Nov):2579-2605, 2008. [
2010 Feb 19
0
"tsne" package for t-SNE dimensionality reduction
I'd like to announce the availability of the "tsne" package. It provides the T distributed Stocastic Neighbor Embedding algorithm by van der Maaten and Hinton: 1. http://ict.ewi.tudelft.nl/~lvandermaaten/t-SNE.html 2. L.J.P. van der Maaten and G.E. Hinton. Visualizing High-Dimensional Data Using t-SNE. Journal of Machine Learning Research 9(Nov):2579-2605, 2008. [
2006 May 30
1
when dimensionality is larger than the number of observations?
Hi, there: Can anyone here kindly point some good reference or links on this topic? Esp. some solutions from BioConductor or R, when dealing with microarray-like, "fat" data? thanks, -- Weiwei Shi, Ph.D "Did you always know?" "No, I did not. But I believed..." ---Matrix III [[alternative HTML version deleted]]
2008 Oct 03
2
computing on expressions
Dear R-users, Suppose I have an expression: expr = expression(a>0) and now I want to modify it to expression(a>0 & b>0). The following doesn't work: expr = expression(expr & b>0) What would be a good way of doing this? Thanks, Vadim ________________________________ Note: This email is for the confidential use of the named addressee(s) only and may contain
2010 Oct 15
1
calling browser on error
Dear R-developers, I am trying to figure out a way to call browser() when an error occur, and naturally I want the browser() to be called in the environment of the error. I tried something simple in vain: > f <- function() { x <- 1; stop('ok') } > tryCatch(f(), error=browser()) Called from: tryCatch(f(), error = browser()) ## if browser() was called in the local environment
2008 Aug 15
1
stopifnot message mutation
Dear R-users, Could someone please explain why the message printed by function stopifnot2, see below, is different from that of stopifnot itself? Thank you for your help, Vadim > stopifnot2 <- function(...) stopifnot(...) > stopifnot(F) Error: F is not TRUE > stopifnot2(F) Error: ..1 is not TRUE > version _ platform i386-pc-mingw32 arch i386 os
2009 Mar 09
1
detecting NULL in recursive lists
Dear R-users, How can I detect a NULL in a recursive list? For a regular list I could use lapply: > lapply(list(x=NULL), is.null) $x [1] TRUE However that doesn't work for structures like list(list(x=NULL)). I tried rapply but it treats NULL as a list and discards them: > rapply(list(a=1, b=list(x=NULL)), is.null) a FALSE Any suggestion? Thank you for your help, Vadim Note:
2008 Nov 28
1
names generated in list indexing
Dear R-devel, When a character vector is used to subscript a list and when some of the subscripts are not present in the list names R returns NULL for those subscripts and generate NA names for each of them: > list(b=1)[c('a','b')] $<NA> <<-- generated name NULL $b [1] 1 Wouldn't it be more intuitive to use the subscript name rather than to generate an NA?
2009 Jul 21
1
bug in approx crashes R
Dear R-devel, The following line crashes R > approx(1, 1, 0, method='const', rule=2, f=0, yleft=NULL, ties='ordered')$y Process R:2 exited abnormally with code 5 at Tue Jul 21 14:18:09 2009 > version _ platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status major 2 minor 9.1 year