similar to: Data frames questions

If I want to do a join based on *two* matching fields in two data frames, can merge() handle this? It appears to only handle a single matching column -- do I need to make a "metacolumn" or is there some way to do this? E.g.: Dataframe 1 contains columns A,B,C and Dataframe 2 contains A,B,D I want an output A,B,C,D which places C and D together if A and B match (otherwise, make two

I'm getting a weird behavior using R 2.5.0 for MacOS X -- I have a csv file with a "properly formatted" date/time field, e.g. After reading in the csv to "hourly_met_data", with a "date" field hourly_met_data$date <- as.POSIXct(hourly_met_data$date) works exactly as it is supposed to (e.g. Min/max of that field are calculated correctly). However, when I

Besides the primary citation, "Kennedy, W. J. Jr and Gentle, J. E. (1980) Statistical Computing Marcel Dekker." (which is $300 and my library doesn't have it), is there any other documentation on how to take a poly() object and predict "by hand" new data? E.g. What do those coefficients actually mean ("The orthogonal polynomial is summarized by the coefficients, which

I apologize for what may be a newbie question: I have two sets of data, one is X,Y,Z data that I'd like to make a contour plot of (Z defining the contours), and a second set of X,Y data (Y as a function of X) which I would like made into a line plot OVERLAYED on the contour plot (X and Y from both plots are in the same units and will have overlapping values). Any suggestions on how to do this

I'm a bit new to writing R functions and I was wondering what the "best practice" for having optional variables in a function is, and how to test for optional and non-optional variables? e.g. if I have the following function: helpme <- function(a,b,c) { } In this example, I want c to be an optional variable, but a and b to be required. How do I: 1) test to see if the user

I'm getting the following error: > headerinfo=readLines(met_station_file,n=8) > headerinfo [1] "Plot Title: tahoe met validation ,,,,,,," [2]Error: invalid multibyte string met_station_file's first 8 lines are as follows: Plot Title: tahoe met validation ,,,,,,, #,"Time, GMT-07:00","Temp, ?F",Coupler Attached,Host Connected,Coupler

I'm trying to redirect where temporary files go under R to D:\temp\somerandomname from its default (C:\Documents and Settings\username\Temp\somerandomname) -- how do I go about doing this? --j -- Jonathan A. Greenberg, PhD Postdoctoral Scholar Center for Spatial Technologies and Remote Sensing (CSTARS) University of California, Davis One Shields Avenue The Barn, Room 250N Davis, CA 95616

I have a numerical vector which contains a (poorly) formatted time column, which, in theory, should be HHMM, but was distributed as an integer, so, for 12:15 am, it is saved as "15" (e.g. HHMM = 0015 with the zeroes stripped). I'm trying to use this in conjunction with strptime, but I'm thinking because each time is an integer ranging from 1 to 4 digits, I probably need to

Quick informal poll: what is everyone's favorite text editor for working with R? I'd like to hear from people who are using editors that have some level of direct R interface (e.g. Tinn-R, Komodo+SciViews). Thanks! --j -- Jonathan A. Greenberg, PhD Postdoctoral Scholar Center for Spatial Technologies and Remote Sensing (CSTARS) University of California, Davis One Shields Avenue The

Rers: I have some ecological data (stream velocity vs. % cover of submerged weeds) that shows strong evidence of a thresholding step-function, e.g. below some velocity, % cover ranges from 0% to 100% (with no apparent relationship to velocity within this range of velocities), but above a certain "threshold" velocity, the % cover does not appear to exceed, say, 10%. There are good

R'ers: I was hoping I could get some direction on this. I have a dataset of the form: Y1,Y2,...,YM = f(X1,X2,...,XN), where N is >>> M The response data (Y1,Y2,...,YM) is frequency data, such that the sum of all Yi = 1.0. Both Xj and Yi are continuous variables. I'm trying to figure out the best approach(es) to solving for the model f() -- any ideas? I could solve

Our lab has a lot of different unix boxes, with different hardware, and I'm assuming (perhaps wrongly) that by setting a per-user package installation directory, the packages will only work on one type of hardware. Our systems are all set up to share the same home directory (and, thus, the same .Renviron file) -- so, is there a way to set, in the .Renviron file, per-computer or

R-helpers: Are there any ways to auto-generate R-friendly (e.g. will pass a compilation check) .Rd files given a set of .R code? How about GUIs that help properly format the .Rd files? Thanks! I want a basic set of .Rd files that I can update as I go, but as with most things my documentation typically lags behind my coding by a few days. --j -- Jonathan A. Greenberg, PhD Assistant Project

R-developers: I'm working on updating my R package "spatial.tools", and one thing I was wondering was the proper way to have hidden functions -- should I simply not export them to the namespace and use the ::: operator to call them (which is what I currently do)? --j -- Jonathan A. Greenberg, PhD Assistant Professor Global Environmental Analysis and Remote Sensing (GEARS)

I'm trying to hunt down an appropriate kriging package for my specific application, and I was hoping someone on the R list might have some pointers -- I'm interested in performing kriging and related spatial interpolations with one of the R packages, but I need to be able to provide my own point-to-point distances (e.g. I do not want to use standard between point distances, as calculated

R-helpers: I need a quick help with the following graph (I'm a lattice newbie): require("lattice") npp=1:5 names(npp)=c("A","B","C","D","E") barchart(npp,origin=0,box.width=1) # What I want to do, is add a single vertical line positioned at x = 2 that lays over the bars (say, using a dotted line). How do I go about doing this?

Quantreggers: I'm trying to run rq() on a dataset I posted at: https://docs.google.com/file/d/0B8Kij67bij_ASUpfcmJ4LTFEUUk/edit?usp=sharing (it's a 1500kb csv file named "singular.csv") and am getting the following error: mydata <- read.csv("singular.csv") fit_spl <- rq(raw_data[,1] ~ bs(raw_data[,i],df=15),tau=1) > Error in rq.fit.br(x, y, tau = tau, ...) :

This is probably a very noobish question, but if I want to create a function that allows an undetermined number of, say, numeric vectors to be fed to it, I would use: myfunction = function(...) { # Do something } Right? If so, how do I a) count the number of vectors "fed" to the function, and b) how do I treat those vectors as variables, e.g. for the call:

R-helpers: It looks like http://finzi.psych.upenn.edu/search.html has stopped spidering the mailing lists -- this used to be my go-to site for searching for R solutions. Are there any good replacements for this? I want to be able to search both functions and mailing lists at the same time. Cheers! --j -- Jonathan A. Greenberg, PhD Assistant Professor Department of Geography University of

Quick question -- if I have a vector of strings that I'd like to split into two new vectors based on a substring that is inside of each string, what is the most efficient way to do this? The substring that I want to split on is multiple characters, if that matters, and it is contained in every element of the character vector. --j -- Jonathan A. Greenberg, PhD Postdoctoral Scholar