R help - Sep 2007 - beginner's questions ... sorry

I have 316 files. Each file represents a patient's breathing track
(respiratory signal recorded for a variable number of cycles). All files
have the same are made up of a header followed by a variable number of
records.
Each record contains 7 comma separated fields.
The patient ID is recorder in the header which is stripped off when reading
the file into a R data.frame.
Since I need to keep this piece of information, I need to add the 8th column
to a patient's data.frame. All elements of such a column store the
patient's
ID.
The problem is trivial. I guess it can be done in a matter of a few seconds.
But I (a R novice) could not find an automatic or fast way to do that.
I started up editing the patient's data.frame and figured out I can only
copy and past 1 cell at a time ... but I had 4991 cells so  ... In addition,
I could not find a way to close the editing session while preserving the
changes in the data.frame.
So I generated a vector with 4991 elements, all recording the same
patient-ID call is patient_ID.
Then I used  *cbind(patient.data.frame, patient_ID)*
to generate a new.patient.data.frame made up of 8 columns, the last added
one recording the patient's ID.

I have no doubt R experienced users would accomplish the same task in a
couple of strokes .... HOW ????

Another question is: how can multiple cells copy&past be performed with R
editor ?
And how shall I instruct R to save my changes when I close the editing
session ?

Thank you very much,
-- 
Maura E.M

	[[alternative HTML version deleted]]

On Thu, Sep 13, 2007 at 03:06:35PM -0500, Maura E Monville
wrote:
> I have 316 files. Each file represents a patient's breathing track
> (respiratory signal recorded for a variable number of cycles). All files
> have the same are made up of a header followed by a variable number of
> records.
You can read the patient ID out of the header using scan and some
manipulation of the resulting strings, depending on how complicated it
is to find the patient ID in the header. 

Then you can read.table or read.csv etc to get the data. Then use the
cbind command as you did to bind the new column with the patient id to
the rest of the data.

I believe that cbind will recycle the patient ID to make up the
required number of rows, so you can simply cbind(your.data,
yourpatientID) where instead of a large column of identical items, you
have a single item for yourpatientID

an example:
> myframe <- cbind(as.data.frame(list(a=1:3,b=3:5)),added="foo")
> 
> myframe
  a b added
1 1 3   foo
2 2 4   foo
3 3 5   foo
> I have no doubt R experienced users would accomplish the same task in a
> couple of strokes .... HOW ????
> And how shall I instruct R to save my changes when I close the editing
> session ?
write.table
write.csv

or my favorite way of keeping data well organized is RSqlite or sqldf
(related)


-- 
Daniel Lakeland
dlakelan at street-artists.org
http://www.street-artists.org/~dlakelan

On 13-Sep-07 20:06:35, Maura E Monville wrote:
> I have 316 files. Each file represents a patient's breathing
> track (respiratory signal recorded for a variable number of
> cycles).
> All files have the same are made up of a header followed by
> a variable number of records.
> Each record contains 7 comma separated fields.
> The patient ID is recorded in the header which is stripped
> off when reading the file into a R data.frame.
> Since I need to keep this piece of information, I need to add
> the 8th column to a patient's data.frame. All elements of
> such a column store the patient's ID.
> The problem is trivial. I guess it can be done in a matter of
> a few seconds.
> But I (a R novice) could not find an automatic or fast way to
> do that.
Hi Maura,
There could be several ways to do it, but the important thing
is to know how to "parse out" the Patient ID from the header.

What is the structure of the header?

One possibility could be to use readline() to read the header
from the file, before reading the file into R as a dataframe.

Then parse out the Patient ID, and assign it to a variable.
Then read in the file as a dataframe, find out how many records
are in it, make a column of that number of copies of the Patient
ID, and glue it onto the dataframe.

Hoping that helps; but if not come back with more info about
that header!

Of course, once you have the Patient ID in a variable to start
with, perhaps you don't need it as part of the dataframe any more?

Best wishes,
Ted.
> I started up editing the patient's data.frame and figured out I can
> only
> copy and past 1 cell at a time ... but I had 4991 cells so  ... In
> addition,
> I could not find a way to close the editing session while preserving
> the
> changes in the data.frame.
> So I generated a vector with 4991 elements, all recording the same
> patient-ID call is patient_ID.
> Then I used  *cbind(patient.data.frame, patient_ID)*
> to generate a new.patient.data.frame made up of 8 columns, the last
> added
> one recording the patient's ID.
> 
> I have no doubt R experienced users would accomplish the same task in a
> couple of strokes .... HOW ????
> 
> Another question is: how can multiple cells copy&past be performed with
> R
> editor ?
> And how shall I instruct R to save my changes when I close the editing
> session ?
> 
> Thank you very much,
> -- 
> Maura E.M
> 
>       [[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 13-Sep-07                                       Time: 21:32:34
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