On Nov 18, 2010, at 10:25 AM, Martin Tomko wrote:
Hi Gerrit,
indeed, that works. Excellent tip!
For reference, I did this:
subset1<-subset(summarystats,(Type==1)&(Class==1)&(Category==1))
I am still not totally sure when one uses "&" amd when "&&" - I was
under the impression that && stands for logical AND....
Both stand for logical AND. "&" is used for vectorized comparisons,
while "&&" will only compare the first elements of the two sides
(usually, but apparently not always) with a warning if there are
longer objects than expected.
> c(1,0,1,0,1) & c(0,0,1,1,-1)
[1] FALSE FALSE TRUE FALSE TRUE
> c(1,0,1,0,1) && c(0,0,1,1,-1)
[1] FALSE
> c(1,0,1,0,1) && c(1,0,1,1,-1)
[1] TRUE
--
David.
Thanks a lot.
Martin
On 11/18/2010 3:58 PM, Gerrit Eichner wrote:
Hello, Martin,
as to your first problem, look at function subset(), and
particularly at its argument "subset".
HTH,
Gerrit
On Thu, 18 Nov 2010, Martin Tomko wrote:
Dear all,
I have searched the forums for an answer - and there is plenty of
questions along the same line - but none of the paproaches shown
worked to my problem:
I have a data frame that I get from a csv:
summarystats<-as.data.frame(read.csv(file=f_summary));
where I have the columns Dataset, Class, Type, Category,..
Problem1: I want to find a subset of this frame, based on values
in multiple columns
What I do currently is:
subset1 <- summarystats
subset1<-subset1[subset1$Class == 1,]
subset1<-subset1[subset1$Type == 1,]
subset1<-subset1[subset1$Category == 1,]
Now, this works, but is UGLY! I tried using "&&" or "&" , for
isntance : subset1<-subset1[ (subset1$Class == 1)&&
(subset1$Category == 1),]
but it returns an empty data frame.
Anyway, the main problem is
Problem2:
I have a second data frame - a square matrix (rownames ==
colnames), distm:
distm<-read.table(file=f_simmatrix, sep = ",");
what I want is select ONLY the columns and rows entries matching
the above subset1:
subset2<-distm[subset1$Dataset,subset1$Dataset] returns a matrix
of correct size, but with incorrect entries (established by visual
inspection).
this is the same as:
selectedrows<-as.vector(subset1$Dataset)
subset2<-distm[selectedrows,selectedrows]
also verified using:
rownames(subset2)%in% selectedrows
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
FALSE FALSE
[13] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
FALSE FALSE
[25] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
FALSE FALSE
[37] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
What am I missing?
Thanks
Martin
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
---------------------------------------------------------------------
AOR Dr. Gerrit Eichner Mathematical Institute, Room 212
gerrit.eich...@math.uni-giessen.de Justus-Liebig-University Giessen
Tel: +49-(0)641-99-32104 Arndtstr. 2, 35392 Giessen, Germany
Fax: +49-(0)641-99-32109 http://www.uni-giessen.de/cms/eichner
---------------------------------------------------------------------
--
Martin Tomko
Postdoctoral Research Assistant
Geographic Information Systems Division
Department of Geography
University of Zurich - Irchel
Winterthurerstr. 190
CH-8057 Zurich, Switzerland
email: martin.to...@geo.uzh.ch
site: http://www.geo.uzh.ch/~mtomko
mob: +41-788 629 558
tel: +41-44-6355256
fax: +41-44-6356848
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
