[R] Getting and using a function
I am trying to do what is perhaps the most basic procedure which can be done with the R software. Under Windows XP Home Edition, I want to get a copy of the function gam, then put it in and use it. I intentionaly use informal terms, rather than technical terms whose exact meaning I might or might not know. I am finding this extremely frustrating. Every time I try to do anything, all I get is error messages. Hey, this isn't rocket science; there are only three or four or five steps involved. Well, what are they? There is all this opaque terminology. There are libraries, and packages, and one downloads them, loads them, and installs them, but just what all this means is unclear. One example among many: I tell it library (gam) all I get is an error message. Error in library (gam) : there is no package called 'gam' Well, does this mean what it says, or does it mean something different? For example, does it mean that such-and-such computer program has not yet been downloaded? I did download and install the 2.4.1 flavor (version?) of the gui. I infer, reading between the lines a bit, that there may be a sort of standard procedure for setting things up, perhaps downloading and installing the utils package, or something. The R software has much gold in it, but, as far as learnability/usability is concerned, I give it poor marks. Tom Jones DrJones at alum.MIT.edu __ [EMAIL PROTECTED] 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.
[R] go or goto command
Some computer languages, including C, have a go or go to command which can be used to shift control to a different part of a function. Question: Does the R language have a corresponding command? (Yes, I am aware that it can be abused; but, in the hands of a good programmer, it is simple to use.) Tom Jones __ R-help@stat.math.ethz.ch 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.
[R] Question about predict function
I am working with a non-parametic smoothing operation using a Generalized Additive Model. It is a bivariate data set. I know how to do the smooth, and out comes a nice smooth curve. Now I want to find the value of the smoothed curve for several values of x (the abscissa). This can be done (please correct me if I am wrong) by using the predict.gam function. You feed the predict.gam function a data frame, telling it what you want. Let's start with the predict.gam function. Are you supposed to be able to look up how to use it? E.g., what goes into the various columns of the data frame? I do have a working function call for predict. It says: pred_out - predict (mod, data.frame (x = x), type = response) (mod is the model) Now, if you tell me that x = x, I will believe you. But what is meant by data.frame (x = x), I know not. Or would it better to call the class, names, and str functions, using some well chosen objects? Tom Jones __ R-help@stat.math.ethz.ch 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.
[R] Extracting the results of a gam smooth
I am conducting a gam smooth and having a devil of a time getting out the answers so I can work with them. Here are the two lines of code: model - gam(y~lo(x, span=0.75, degree=2), family=poisson) resp_pout - predict (model, data.frame (x=x), type = 'response') The problem comes when I try to get the answers out. I cannot for the life of me figure out the format of resp_pout, and I have been trying literally for WEEKS to get the answer. Surely this is a perfectly standard question which has been asked and answered dozens of times. Let's see if I can rephrase the question. There are 118 response points generated by the smoothing operation. I need a function f such that v - f(resp_pout) is a vector with 118 components comprising the 118 response points. Would some kind soul provide it? Or is my entire research effort going to be BLOWN UP because I can't figure out how to do this? Thomas Jones __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] Finding the format of an object redux
Okay, I am dealing with an object. Without going into too much detail, a gam (Generalized Additive Model) is involved. Assume that the name of the object is obj without the quotes. I tell it: print (obj) inside a function. I get out a bunch of pairs of lines. (1) Odd-numbered lines are integers. (2) Even-numbered lines have real/floating point numbers. For example, the first two lines are: 1234567 8 5.354175 5.328358 5.293970 5.264434 5.235172 5.206112 5.177180 5.148305 [snip] The last two integers are 117 and 118; the corresponding real numbers are 4.354862 and 4.196938. Jeepers, creepers, what does all this -MEAN?- Are the integers part of the object, or are they indices or subscripts or names or something? The value of class (obj) is numeric including the quotes. The value of is.numeric (obj) is TRUE. The value of length (obj) is 118. Well, is this a data frame or a matrix or a table or a vector whose elements are vectors of length two? Or a vector with two elements, each of which is a vector of length 118? Surely there is a way of finding out the answer to this question. Every time I look at the documentation, it just tells me to look somewhere else. Is there a function f such that f (obj) will tell you a little bit about the format of the object? Tom Thomas L. Jones, Ph.D., Computer Science __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] Finding out the format of an object
Suppose I have an arbitrary R object. Is there a way to find out its format? There are 118 points, each described by two numbers. Let the name of the object be obj without the quotes. I can do a print (obj), but all I get is a bunch of numbers. I can do a ls.str (obj), but all I get is a bunch of numbers. Is it a data frame? A vector with 118 elements, each having two sub-elements? Or ---? The object in question is of the class gam (Generalized Additive Model). I know how to pull out some data with the predict function, but, when I try to print the value of the predict function, all I get is a bunch of numbers. Also, how could I have looked this up without having to post a question here? Tom Thomas L. Jones, Ph.D., Computer Science __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] Debugging a program written in the R language
From Tom: The subject is debugging a program written in the R language,under Windows. (Sorry, but I do not know either the Apple OS or *nix.) A computer program will usually not work on the first try, if only because of the risk of typos. Instead, it must be debugged. Roughly, here is the sequence: (1) One codes a program using the R language, and stores it on the hard drive, using some particular editor. (2) The program is fed to the R software, together with test data, etc. (3) A test computation is run and bugs are spotted. (4) The program is corrected, using an editor, and the revised version is stored on the hard drive. (5) The sequence goes back to step (2) and is repeated until the program hopefully works. Unfortunately, the documentation doesn't really explain how to do all of this, or if it is explained in the documentation, I can't find it. Reading between the lines a bit, I infer that you are supposed to be able to use something called a History file, then sort of work backward in the code and make corrections. I never got it to work for me. Also, it is unclear how you would handle code entered six weeks or six months ago. That is the bad news; the good news is that some kind soul told me about a key trick; prepare the program in Windows text format (.txt) and copy it and paste it into the console. The program will now run from a user-defined wrapper or driver function. I am aware that there is an editor called Emacs which you can use if you are a member of the *nix community, which I am not. Question: How are you -supposed- to debug a program which you have written in the R language? Tom Thomas L. Jones, Ph.D., Computer Science __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] How do I tell it which directory to use?
From Tom: In R 2.2.0 under Windows, I want to be able to give it a filename such as myFile.txt without the quotes. But actually I mean: C:\Documents and Settings\Tom\My Documents\qpaper7\R Project Started 19 Dec 05\myFile.txt If I were to repeat this each time, my computer would get all bored and cranky and start to drop bits (only a joke, of course). I think I want to set the Home directory or the working directory or some directory or other to the above directory. I may or may not want to set some environmental variables. R 2.2.0; working directly from the console and copying and pasting code which I want to test into the console. Windows XP Home Edition. Administrator privileges are enabled. A curve ball: There are two accounts, Tom and Jones; the data are stored under Tom, whereas the computation is being done under the Jones account. I won't bore you with the details of why I am doing this. I was able to call Sys.getenv (R_USER) and get the home directory. I am a newbie to R and not familiar with the terminology. Tom Thomas L. Jones, Ph.D., Computer Science __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] Scatterplot with corner at (0, 0)
I have two vectors, x and y, and I want to create a scatterplot. I want the lower left corner to be at (0, 0). I can create a scatterplot just by calling plot (x, y), but I am quite throroughly stymied and frustrated by the problem of putting the lower left corner at (0, 0), despite many tries. Thomas L. Jones, Ph.D., Computer Science __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] (newbie) Saving the workspace in .txt format
(newbie question) How do I save the workspace in Windows text format (with the file extension .txt)? Also, having saved it and edited it, how do I load it back into the workspace? The setup is: Windows XP Home Edition Service Pack 2 R 2.2.0 English language Administrator privileges are enabled Tom Jones, a veteran computer professional who is a newbie to R __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] Defining and running a simple function
I am trying, with extremely limited success, to get the R software to
do some simple computations. Specifically, I defined a test function
as follows:
fn - function () {
hw - hello world
hw
s - seq (0, 0.98, 0.02)
s
}
The output should just be the words hello world, followed by a
sequence going from 0 to 0.98.
However, when I call the little test function:
fn ()
the words hello world get lost and do not come out. Instead, the
output begins with
[1] 0.00 0.02, etc
However, when I write a test function for just the words hello
world, the words come out just fine.
Here is the setup:
R-2.2.0 using the English language and the console
Windows XP Home Edition Service Pack 2
AVG Antivirus Free Version
Windows built-in firewall
The R buffered output is disabled.
Mozilla Firefox 1.5
Administrator privileges are enabled.
Your advice?
Tom Jones
__
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https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] Newbie question--locally weighted regression
I have a dataset, a time series comprising count data at five minute intervals. These are the number of people who voted at a particular voting place during a recent election. The next step is to smooth the data and estimate a demand vs time-of-day function; the problem is of interest in preventing long lines at voting places. I am using the R Project software. However, I am not a statistician, and I am somewhat baffled by how to do the smoothing. These are integers with roughly Poisson distribution, and the use of a least-squares regression would create large errors. Apparently something called a link function factors into the equation somehow. Question: Do I want a link function? If so, do I want a logarithmic link function? Unless I change my mind, I will use lowess or loess for the smoothing; how do I tell it to use a link function? Doc __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] An embarrassment of riches
I have a dataset which I am trying to smooth, using locally weighted regression. The y values are count data, integers with Poisson distribution, and it is important for the regression function to know this, since assuming a Gaussian distribution will lead to substantial errors. It is a time series; the x values have equal five minute intervals. Here is the problem: I have an embarrassment of riches. Unless I am mistaken, the following R packages will do this: locfit, aws, sm, gss, semipar, pgam, gregmisc, to name just a few. Questions: Which package should I use, and which function in the package should I use for the regression? Here is the Google search result, restricted to r-project.org: http://www.google.com/search?as_q=locally+weighted+poisson+regressionnum=10hl=enbtnG=Google+Searchas_epq=as_oq=as_eq=lr=as_ft=ias_filetype=as_qdr=allas_occt=anyas_dt=ias_sitesearch=r-project.orgas_rights=safe=images If the above hyperlink does not work, please try http://tinyurl.com/exw7e Doc __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] Bookmarking a page inside r-project.org
By way of review, most large Web sites allow the user to create *bookmarks* which link to pages inside the Web site. However, here, the pages have one of just two URL's: http://www.r-project.org and http://cran.r-project.org The reason is the way HTML *frames* are used in setup of the Web site. It would be very helpful if the Web site were revised so that many if not most pages had their own URL's, allowing the use of bookmarks. Tom Thomas L. Jones, Ph.D., Computer Science __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] More on bookmarking a page
The subject is how to bookmark a page inside r-project.orgFrom Peter Dalgaard:At least in Firefox, one thing you can do is to bring up the relevant link in a new window or tab (just right-click it) and bookmark that.From Thomas Jones:Well, learn something every day! I stand corrected. __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] loess smoothing question
I am trying to smooth a dataset with evenly spaced values of x, perhaps using loess smoothing or something similar. However, the y values are hypergeometrically distributed; I think I want to use a logarithmic link function. It falls under the general heading of non-parametric regression. The problem is of interest in predicting the demand at a voting place, in order to avoid long lines. Questions: Should I use loess smoothing? Do I want a logarithmic link function? If so, How do I tell loess to use a logarithmic link function? Tom, a newbie to the R project, and not really a statistician __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
