search for: surrogation

I have a question on generating multivariate time series surrogates using the "surrogates" function in the RTisean library. The surrogate data matrices are always much shorter than the input matrices. FYI, I'm using R version 2.12.2 on Windows XP RTisean library v 3.0.14 Tisean algorithms v 3.0.13 Creating a surrogate univariate time series returns a time series with the

Dear R, Short verse of the question: Is there R code which will calculate surrogate splits and/or delta impurity for decision trees at each node? Long Version: I have local, legacy code which I use to calculate my decision trees. I would like to switch to R, but as I understand it surrogate splits are not implemented. Surrogate splits and feature ranking are described in Breiman et al

R helpers, I am working with the R program performing multivariate regression trees (MRT). I have a matrix with species and environmental variables saved as a CSV file (sprot_matrix.csv), I have 42 species and 8 environmental variables (SECCHI+PH+TA+PTOT+NTOT+CHLA+AREA+ MEANDEP) for 104 samples Title SpA SpB SpC SpD Varible1 Variable2 Variable3 Sample1 Sample 2

Dear R-help, I would like to compute the variance for the proportion of treatment effect by a surrogate in a survival model (Lin, Fleming, and De Gruttola 1997 in Statistics in Medicine). The paper mentioned that the covariance matrix matches that of the covariance matrix estimator for the marginal hazard modelling of multiple events data (Wei, Lin, and Weissfeld 1989 JASA), and is implemented

As per `?intToUtf8`, and in the comments to `valid_utf8`[1], R intends to prevent illegal UTF-8 such as UTF-8 encoded UTF-16 surrogate pairs.? `R_nchar`, invoked via `base::nchar`, explicitly validates UTF-8 strings[2], but allows the surrogate: ??? > Encoding('\ud800') ??? [1] "UTF-8" ??? > nchar('\ud800')? // should be an error ??? [1] 1 The problem manifests

R helpers, I would like to know if it is possible that the last version of R is not giving the surrogate splits when you perform a Multivariate regression tree analysis? I installed the programm in different computers and i run the some matrix and it didn't gave me this information. With a previus version R 2.1.1. I do get the information for the surrogates. Please let me know how to get the

Dear R-help, I'm applying the surrogate Poisson glm, by following Venables & Ripley (7.3 pp238-42). >overall_cbind(expand.grid(treatment=c("Pema","control"),age=c("young","adult","old"),repair=c("excellent","good","poor")),Fr=c(8,0,7,1,2,0,2,7,1,4,7,1, 0,3,2,5,1,9))

For ordered factor the natural contrast coding would be to parametrize by the succsessive differences between levels, which does not assume equal spacing of factor levels as does the polynomial contrasts (implicitly at least). This requires the contr.cum, which could be: contr.cum <- function (n, contrasts = TRUE) { if (is.numeric(n) && length(n) == 1) levs <- 1:n

Hello all, I am working on building a web store with RoR. The company has many locations. All the stock/order information is processed through the same site. Here is my question. How would you handle the multiple warehouse problem with Rails? How would you keep track of the information in multiple warehouses? Thank you for your help, PV -- Posted via http://www.ruby-forum.com/.

These utility functions will be used in the OCaml inspection code. --- daemon/daemon_utils_tests.ml | 15 +++++++ daemon/utils.ml | 100 +++++++++++++++++++++++++++++++++++++++++++ daemon/utils.mli | 12 ++++++ 3 files changed, 127 insertions(+) diff --git a/daemon/daemon_utils_tests.ml b/daemon/daemon_utils_tests.ml index 892509d89..b1f02de30 100644 ---

--- included message ---- Thus, my question is: *What common measures exists for ranking/measuring variable importance of participating variables in a CART model? And how can this be computed using R (for example, when using the rpart package)* ---end ---- Consider the following printout from rpart summary(rpart(time ~ age + ph.ecog + pat.karno, data=lung)) Node number 1: 228 observations,

I have a table that is to hold all ISO 639 language codes: alpha3t, alpha3b, alpha2, that bunch. It also (indirectly) holds language names, but that''s off-topic. alpha3t is the primary key, so I''ve told Active Record about this by saying set_primary_key "alpha3t" within the Language model. (Don''t try to call your models things like ISO639 (won''t work

Does anyone know a reason why, in principle, a call to randomForest cannot accept a data frame with missing predictor values? If each individual tree is built using CART, then it seems like this should be possible. (I understand that one may impute missing values using rfImpute or some other method, but I would like to avoid doing that.) If this functionality were available, then when the trees

Hi, When I look at the summary of an rpart object run on my data, I get 7 nodes but when I plot the rpart object, I get only 3 nodes. Should the number of nodes not match in the results of the 2 functions (summary and plot) or it is not always the same? Look forward to your reply, Carol -------------------------------------------- ?summary(rpart.res) Call: rpart(formula = mydata$class ~ ., data

Hi all, I started playing a couple days ago with Rails and it find it very interesting. But I''m a bit stuck with making it work with a concatenated primary key. I want to use my own names for the DB fields and I''m using SQL Server 2005. My tables look roughly like this: CREATE TABLE USERS ( USR_ID VARCHAR(25) NOT NULL PRIMARY KEY, USR_PASS VARCHAR(25) ) CREATE TABLE

Dear R users, I’m trying to understand how correlated predictors impact the Relative Importance measure in Stochastic Boosting Trees (J. Friedman). As Friedman described “ …with single decision trees (referring to Brieman’s CART algorithm), the relative importance measure is augmented by a strategy involving surrogate splits intended to uncover the masking of influential variables by others

Hi everyone, I've noticed new behavior in `regexpr(..., perl = TRUE)` on Windows with R4.0 and above with Unicode characters. Here's a minimal example where I'd expect to see a start value of `5` (as R 3.6.2 and below gives), but R 4.0.0 (and R 4.0.1) now returns: ``` > regexpr("b", "foo\U0001F937bar", perl = TRUE) #> [1] 6 #>

Dear r-help, I am trying to build a new function (to process rpart objects) that will output matrix that has a row for each node and a column for each feature. With each entry in the table is a numerical property at that node for that feature (e.g. surrogate split agreement, improvement). My current trouble is that the only clue to the identity of the feature is stored as the *name* of the

Have been looking into using rails but am finding the "Composite Primary Keys are Bad" thing a tad disturbing (to put it mildly). I have been working with RDBMS systems for over fifteen years and this is the first time I have herd the idea questioned. I have cone across using surrogate keys which mirror the composite key for performance reasons in VERY big databases but I have never

Assume I have the following example hierarchy: US >Michigan >>Detroit >>Grand Rapids >>Lansing >Minnesota >>Grand Rapids >>Minneapolis >>St Paul >Ohio >>Columbus >>Grand Rapids >>Sandusky I see two ways that I could index a ?Grand Rapids, Michigan? document with prefixed terms: XFIRSTLEVELus XSECONDLEVELmichigan