Description Usage Arguments Details Value Note Author(s) References See Also Examples
Applies the UfsCov algorithm based on the space filling concept, by using a sequatial forward search (SFS).This function offers a parellel computing.
1 | UfsCov_par(data, ncores=2)
|
data |
Data of class: |
ncores |
Number of cores to use (by default: |
Since the algorithm is based on pairwise distances, and
according to the computing power of your machine, large number of
data points needs more memory. See UfsCov_ff
for memory
efficient storage of large data on disk and fast access (by using the
ff
and the ffbase
packages).
A list of two elements:
CovD
a vector containing the coverage measure of
each step of the SFS.
IdR
a vector containing the added variables during
the selection procedure.
The algorithm does not deal with missing values and constant
features. Please make sure to remove them. Note that it is not recommanded to
use this function with small data, it takes more time than using the
standard UfsCov
function.
Mohamed Laib Mohamed.Laib@unil.ch
M. Laib and M. Kanevski (2017). Unsupervised Feature Selection Based on Space Filling Concept, arXiv:1706.08894.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | N <- 800
dat<-Infinity(N)
Results<- UfsCov_par(dat,ncores=2)
cou<-colnames(dat)
nom<-cou[Results[[2]]]
par(mfrow=c(1,1), mar=c(5,5,2,2))
names(Results[[1]])<-cou[Results[[2]]]
plot(Results[[1]] ,pch=16,cex=1,col="blue", axes = FALSE,
xlab = "Added Features", ylab = "Coverage measure")
lines(Results[[1]] ,cex=2,col="blue")
grid(lwd=1.5,col="gray" )
box()
axis(2)
axis(1,1:length(nom),nom)
which.min(Results[[1]])
## Not run:
N<-5000
dat<-Infinity(N)
## Little comparison:
system.time(Uf<-UfsCov(dat))
system.time(Uf.p<-UfsCov_par(dat, ncores = 4))
## End(Not run)
|
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