Dear R Users, I have created a 1500 x 20000 data frame - DataSeq. Each of the 1500 rows represents a data sequence. I have another data frame iData that stores the information of these 1500 data sequences in the same order, for example, condition, gender, etc. If I use "subset" to select certain groups within iData according to some criteria that I have set, e.g. condition, gender Then how can I used the retrieved subset of iData to point to and retrieve corresponding rows in the DataSeq data.frame for manipulations and analysis? I hope some of you can give me some idea! Thank you very much!!! - John
index to select rows of a large matrix
4 messages · tsunhin wong, jim holtman
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Dear Jim,
Thanks for your suggestion.
I have a follow-up question for fellow R Users that have followed this thread:
*I used to create two lists by some very flexible criteria to compare
from "iData" and pass the two lists to *ANOTHER FUNCTION* that further
decompose the two lists and do some case by case analysis:
comp.lst[[1]] <- subset(iData,(Session==1 & TrialList==2 & BadTrial==0
& Correct==1 & Critical.BT>0))
comp.lst[[2]] <- subset(iData,(Session==2 & TrialList==2 & BadTrial==0
& Correct==1 & Critical.BT>0))
*The function will then do some subject by subject processing:
tmplist <- comp.lst[[1]]
subject <- unique(tmplist$Subject)
Psubjmatrix <- NULL
for(j in 1:length(subj)) { ##divide the list and process per subject in the list
subjtriallist <- subset(tmplist,(Subject==subj[j])) ##divide
the list and process per subject in the list
print(paste("Start working on Subject ",subj[j],sep=""),quote=FALSE)
##The sub-divided list is passed to another function to
extract data from corresponding object
Ptrialmatrix <- SeekObject(subjtriallist,seconds,samplesize,sdmax);
##add rowmean to subject pupil matrix
Psubjmatrix <- cbind(Psubjmatrix, rowMeans(Ptrialmatrix,
na.rm=TRUE, dims=1))
}
*But now, I have a pre-processed the objects and cooked up a
1500x20000 matrix, and there is no need to get these objects one by
one for extraction, I may just do the following:
Ptrialmatrix <- PMasterMatrix[subjindex,,drop=FALSE]
*However, on passing the index to the function, I cannot further
sub-divide the list index by Subject.
I have been thinking of passing the criteria to within the function.
But... what smarter thing I can do to make it works?
- John
On Thu, May 21, 2009 at 10:33 AM, jim holtman <jholtman at gmail.com> wrote:
Assuming that you get the list of indices into iData for the criteria, then you can use that to get the appropriate rows: indx <- which(iData >5)? # or whatever your criteria is DataSeq[indx,, drop=FALSE]? # gives you a subset matrix of just the rows you are interested in. On Thu, May 21, 2009 at 10:10 AM, tsunhin wong <thjwong at gmail.com> wrote:
Dear R Users, I have created a 1500 x 20000 data frame - DataSeq. Each of the 1500 rows represents a data sequence. I have another data frame iData that stores the information of these 1500 data sequences in the same order, for example, condition, gender, etc. If I use "subset" to select certain groups within iData according to some criteria that I have set, e.g. condition, gender Then how can I used the retrieved subset of iData to point to and retrieve corresponding rows in the DataSeq data.frame for manipulations and analysis? I hope some of you can give me some idea! Thank you very much!!! - John
______________________________________________ R-help at 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.
-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve?
Dear all, I found the answer: intersect() - John
On Thu, May 21, 2009 at 7:32 PM, tsunhin wong <thjwong at gmail.com> wrote:
Dear Jim,
Thanks for your suggestion.
I have a follow-up question for fellow R Users that have followed this thread:
*I used to create two lists by some very flexible criteria to compare
from "iData" and pass the two lists to *ANOTHER FUNCTION* that further
decompose the two lists and do some case by case analysis:
comp.lst[[1]] <- subset(iData,(Session==1 & TrialList==2 & BadTrial==0
& Correct==1 & Critical.BT>0))
comp.lst[[2]] <- subset(iData,(Session==2 & TrialList==2 & BadTrial==0
& Correct==1 & Critical.BT>0))
*The function will then do some subject by subject processing:
tmplist <- comp.lst[[1]]
subject <- unique(tmplist$Subject)
Psubjmatrix <- NULL
for(j in 1:length(subj)) { ##divide the list and process per subject in the list
? ? ? ?subjtriallist <- subset(tmplist,(Subject==subj[j])) ##divide
the list and process per subject in the list
? ? ? ?print(paste("Start working on Subject ",subj[j],sep=""),quote=FALSE)
? ? ? ?##The sub-divided list is passed to another function to
extract data from corresponding object
? ? ? ?Ptrialmatrix <- SeekObject(subjtriallist,seconds,samplesize,sdmax);
? ? ? ?##add rowmean to subject pupil matrix
? ? ? ?Psubjmatrix <- cbind(Psubjmatrix, rowMeans(Ptrialmatrix,
na.rm=TRUE, dims=1))
}
*But now, I have a pre-processed the objects and cooked up a
1500x20000 matrix, and there is no need to get these objects one by
one for extraction, I may just do the following:
Ptrialmatrix <- PMasterMatrix[subjindex,,drop=FALSE]
*However, on passing the index to the function, I cannot further
sub-divide the list index by Subject.
I have been thinking of passing the criteria to within the function.
But... what smarter thing I can do to make it works?
- John
On Thu, May 21, 2009 at 10:33 AM, jim holtman <jholtman at gmail.com> wrote:
Assuming that you get the list of indices into iData for the criteria, then you can use that to get the appropriate rows: indx <- which(iData >5)? # or whatever your criteria is DataSeq[indx,, drop=FALSE]? # gives you a subset matrix of just the rows you are interested in. On Thu, May 21, 2009 at 10:10 AM, tsunhin wong <thjwong at gmail.com> wrote:
Dear R Users, I have created a 1500 x 20000 data frame - DataSeq. Each of the 1500 rows represents a data sequence. I have another data frame iData that stores the information of these 1500 data sequences in the same order, for example, condition, gender, etc. If I use "subset" to select certain groups within iData according to some criteria that I have set, e.g. condition, gender Then how can I used the retrieved subset of iData to point to and retrieve corresponding rows in the DataSeq data.frame for manipulations and analysis? I hope some of you can give me some idea! Thank you very much!!! - John
______________________________________________ R-help at 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.
-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve?