[R] readMat - how to retrieve the variables
dwinsemius at comcast.net
Mon Mar 14 00:00:50 CET 2011
On Mar 13, 2011, at 6:42 PM, Eduardo M. A. M.Mendes wrote:
> Hi Joshua
> Many thanks.
> The values of flow can be accessed in a weird way and we can used
> them for some calculations. Since I am a newbie as far as using R
> is concerned I wonder whether you could tell me how to create a
> structure in R that looks like the one I have in matlab (that is, a
> variable a that contains river1 and river2 that contains flow and
If you posted the results of dput(a) , we might be able to test our
pet theories, but here is my hapless first guess:
mat.R.struc <- with(b$a[,,1], #looks like it was a matrix that had
lists as elements
cbind(as.data.frame(river1), as.data.frame(river2) )
It's not so much that it will "look like" your Matlab structure, but
it could be something that you can work with. This will create a long-
format structure which is a typical one for plotting ans regression.
Another option would be an R array which, unlike matrices, can have
more than 2 dimensions.
> -----Original Message-----
> From: Joshua Wiley [mailto:jwiley.psych at gmail.com]
> Sent: Sunday, March 13, 2011 7:20 PM
> To: Eduardo M. A. M.Mendes
> Cc: R-help at r-project.org
> Subject: Re: [R] readMat - how to retrieve the variables
> On Sun, Mar 13, 2011 at 2:56 PM, Eduardo M. A. M.Mendes <emammendes at gmail.com
> > wrote:
>> Hi Joshua
>> Many thanks for the prompt reply.
>> I have saved a short version of the matlab file and the output on R
>> , , 1
>> river1 List,2
>> river2 List,2
> It looks like you are dealing with a special series of lists nested
> within three dimensional arrays within lists. My suggestion would
> be to double check that the matlab file has reasonable data
> (whatever that means) and try to double check your use of readmat
> (do you meet all the requirements for versions, etc.). That is not
> a common R structure so the extraction is similarly uncommon.
> Perhaps Henrik will be along with more helpful answers.
> Good luck,
>>  "MATLAB 5.0 MAT-file, Platform: PCWIN, Created on: Sun Mar 13
>> 18:51:54 2011 "
>>  "5"
>>  "little"
>> When I issue the command b$a[,,1]$river1[,,1]$flow I see the flow
>> Unfortunately the data is confidential.
>> Many thanks
>> -----Original Message-----
>> From: Joshua Wiley [mailto:jwiley.psych at gmail.com]
>> Sent: Sunday, March 13, 2011 6:30 PM
>> To: Eduardo M. A. M.Mendes
>> Cc: R-help at r-project.org
>> Subject: Re: [R] readMat - how to retrieve the variables
>> Hi Ed,
>> Can you please provide *at least* the R output from running:
>> where "data" is the variable name you stored the results of
>> readMat() in. If it is reasonably small and can be sent as
>> plaintext (I do not know Matlabs file format off hand), you could
>> send us the actual data so we can try to read it in, but at the
>> least str() will let us see how R is storing your data and give you
>> some explanation.
>> Side note, as data() is a function, it might be worthwhile to call
>> your actual data something else (say, mydata, dat, etc.). For
>> anyone else interested, readMat() is in package "R.matlab".
>> On Sun, Mar 13, 2011 at 2:07 PM, Eduardo M. A. M.Mendes <emammendes at gmail.com
>> > wrote:
>>> I have a matlab MAT file that contains one single variable: a. The
>>> structure of a is as follows:
>>> a.river1.flow (flow values)
>>> a.river1.date_flow (date)
>>> a.river1.precip (precipitation values) a.river1.date_precip
>>> a.river2.flow a.river2.date_flow a.river2.precip
>>> I have used readMat to load the variable a in R, however I have no
>>> idea how readMat translates a. I managed to get some values out of
>>> data$a[,,1]$river1[,,1]$flow -> Why do I need [,,1]? Why not
>>> Many thanks
>>> R-help at r-project.org mailing list
>>> PLEASE do read the posting guide
>>> and provide commented, minimal, self-contained, reproducible code.
> Joshua Wiley
> Ph.D. Student, Health Psychology
> University of California, Los Angeles
> R-help at r-project.org mailing list
> 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
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