search for: witthoft

Hi, A recent thread provided a (working) construct for lm: lm(as.matrix(freeny[ix]) ~., freeny[-ix]) Can someone explain what is meant by the formula in that expression, that is, what does "mymatrix~." do? I couldn't find any such example in the lm() or formula() help pages. thanks Carl

This is not the same as the recent thread on a waterfall graph. I'm thinking about the rolling FFT display used in acoustics and other spectrum analysis tasks. Here's an example of a very fancy 3-D waterfall display: http://www.ultimaserial.com/UltimaWaterfall.html I was just wondering if there are any simple hidden-line tools in R that I could use to draw simple waterfall displays.

Let's say I have, for some reason, a bunch of scalars (i.e. single-valued variables) and I want to merge them all into a single vector of values. Can someone recommend a better function, or simpler way, to do so than the following? Suppose my scalars' names are foo1, foo2, foo3, foo1high, foo2high, foo3lo2, etc. Then I can do: >ls(pat='foo')->thels

Hi, So far as I can tell, the 'col.ticks' parameter for axis() only uses the first value provided. E.g.: plot(0:1,0:1, col.ticks=c('blue','red','green')) #all ticks are blue Just wondering if there's a different option in the basic plot commands that can handle multiple colors, and also whether ggplot and/or lattice allow for multiple tick colors.

Hi, While playing with quantile-quantile plots, I wrote up some code which plots something strangely different. Here's the pseudocode: testhist <- hist(sample_data) refhist <- hist(rnorm(n, mean=0,sd=1)) # for some large-ish n cumtest <- cumsum(testhist) cumref <- cumsum(refhist) plot(cumref,cumtest) This produces a straight line of slope 1 for a sample with the same

Hi, Sorry to bother with something that should be simple, but I can't find it. Suppose I have a list, each element of which is a 2xN dataframe, where N could be different for each element. Is there some simple structure to let me examine all the elements of each element's first column? For example: >foo $first [,1] [,2] [1,] 1 4 [2,] 2 5 [3,] 3 6 $second

Hi, subject more or less says it all. I freely admit to not having bothered to find some of the online papers about method of testing the quality of random number generators -- but in an idle moment I wondered what to expect from something like the following: randa<-runif(1000) randb<-runif(1000) t.test(randa,randb)$p.value var.test(randa,randb)$p.value [repeat ad nauseum] Is the

No, seriously: I've had more than one person at work wonder what math toolset could be loaded onto iOS. So, before Matlab, FreeMat, Mathematia, SciLab, Octave, or numpy (:-) ) produces a version for iPad, any chance someone is working on R for iPad?

Hi, I'm relatively new to R, so I don't know the full list of base (or popular add-on packages) functions and tools available. For example, I tripped across mention of rle() in a message about some other problem. rle() turned out to be a handy shortcut to splitting some of my data by magnitude (vaguely like a sequence-based histogram). So I thought I'd ask: what small, or

I followed a couple threads from the archives and from stackoverflow.com, and would like to know: just what is "..." ? What I mean by this is,for example, from the point of view of a user running a function in debug mode, is "..." an object, or does it exist in the current environment as some thingy? Maybe a better question to ask is: if I were to write some function

I was cursing Matlab again today (what else is new) because the default action for every Matlab command is to spew the result to the console, and one must remember to put that darn ";" at the end of every line. So I just wondered: was there ever a discussion as to providing some modified version of the "<-" and "->" operators in R to do the reverse?

Hi, I've got a matrix, Z, of values representing (as it happens) optical power at each pixel location. Since I know in advance I've got a single, convex peak, I would like to do a 2D parabolic fit of the form Z = poly((x+y),2) where x and y are the x,y coordinates of each pixel (or equivalently, the row, column numbers). Is there an R function that lets me easily implement that?

Here's the problem: on Windows, the 'jgr.exe' tool starts up by checking for a connecting to the 'net in order to grab the support packages. Well, we have machines at work that are not and never will be connected to the Internet. I tried manually installing all the packages (JGR, Rjava, etc) but the jgr.exe still tries to find a connection. Is there any way around this?

Just wondering how come read.table lets you specify fill=TRUE for ragged arrays, but so far as I can tell, no equivalent for write.table? Not a big deal, since I'm perfectly comfortable w/ write and scan and the other file I/O goodies. "A foolish inconsistency..." and all that. Carl

Hi all, Just thought I'd post this (maybe) helpful tool I wrote. For people like me who are bad at keeping a clean environment, it's a time-saver. #simple command to get only one type of object in current environment lstype<-function(type='closure'){ inlist<-ls(.GlobalEnv) if (type=='function') type <-'closure'

Just wondering if there's an R package which does tricks similar to what TK!Solver does. TK!Solver, for those not lucky enough to have found it, basically allows one to define a bunch of equations, assign values to an arbitrary subset of the variables, from which it calculates (either directly when possible or back-solving when not) the values of the other variable(s). thanks Carl

I know how to set graphic parameters by calling par(), but what I'd like is a way to set the default values so that subsequent calls to par() use my defaults. The reason to want this is that every time I create a new graphic window (I'm using quartz on OSX, and so far no answers in the Mac mailing list), my parameters get reset to the builtin defaults. I read about the

Hi all, I'd like to plot the Real and Imaginary parts of some f(z) as two different surfaces in wireframe (the row/column axes are the real and imag axes). I know I can do it by, roughly speaking, something like plotz <- expand.grid(x={range of Re(z)}, y={range of Im(z), groups=1:2) plotz$func<-c(Re(f(z),Im(f(z)) wireframe(func~x*y,data=plotz,groups=groups) But that seems like a

First, let me apologize in advance if this is the wrong place to submit a suggestion for a change to functions in the base-R package. It never really occurred to me that I'd have an idea worthy of such a change. My idea is to provide an upgrade to all the "sets" tools (intersect, union, setdiff, setequal) that allows the user to apply them in a strictly algebraic style. The

Hello, I am trying to filter a data set like below so that the peaks in the Phase value are more obvious and can be identified by a peak finding function following the useful advise of Carl Witthoft. I have written the following for(i in length(data$Phase)){ newphase=if(abs(data$Phase[i+1]-data$Phase[i])>6){ data$Phase[i+1] }else{data$Phase[i] } } I get the following error which I have not seen before when I paste the code into R Error in if (abs(data$Phase[i + 1] - data$Phase[i]) > 6...