similar to: Subset and order at the same time?

Hi, I'm having difficulty coming up with a good way to subest some data to generate statistics. My data frame has multiple observations by group. Here is an overly-simplified toy example of the data ========================== code v1 v2 G1 1.2 2.3 G1 0 2.4 G1 1.4 3.4 G2 2.9 2.3 G2 4.3 4.4 etc.. ========================= I want to normalize the data *by group* for certain variable.

Hello, I need to calculate a moving average and an exponentially weighted moving average over a fairly large data set (500K rows). Doing this in a for loop works nicely, but is slow. ewma <- data$col[1] N <- dim(data)[1] for(i in 2:N){ data$ewma <- alpha * data$ewma[i-1] + (1-alpha) * data$value[i] } Since the moving average "accumulates" as we move through the data,

Hi, I'm interested in doing some sound analysis with R. Does anyone have any experience/methods for reading in a wav file? -- Noah Silverman UCLA Department of Statistics 8208 Math Sciences Building Los Angeles, CA 90095 [[alternative HTML version deleted]]

Hi, i have some data in a matrix. It has zero values scattered throughout, at random. I'd like to create a line plot, with a line for each row, that *excludes* the zero or NA values. The data looks like this (toy example) 10 12 21 0 23 0 43 0 NA 41 0 0 0 34 35 0 35 0 44 0 NA NA NA 3 2 5 0 3 2 etc... Suggestions on an easy way to do this? Thanks! -- Noah Silverman UCLA Department of

Hi, I have a rather large data frame (500 x 5000) that I want to convert to a proper xts object. I am able to properly generate an xts object with the correct time index. However, all of my numerical values are now strings. b <- as.xts(a[,2:dim(a)[2]], order.by=as.POSIXct(strptime(paste(a$Date), '%m/%d/%Y'))) My guess is that somewhere in the large data frame there are a few

Hi, I want to keep a running file of some statistics generated by a running process. Occasionally the process will be restarted. On restart, I'd like to read the last line of the log file to set some variables to their last state, and then continue to append values to that same file. I can't seem to get the appending part to work. I can read values form the file, but then upon the

Hello, I noticed something odd when working with data frames and xts objects. If I read in a CSV file, R creates a nice data.frame. This works well. If I then convert to an XTS object, I see that all the values in the data are now quoted. My data is a mix of numeric and character. This is usually seen when converting a data.frame to a matrix, as R will treat all the data as the same class.

Hi, I'm looking at the "cocktail party" classic problem. I can see how to use ICA to separate the components. But, How do I then create new wav files of the separated sounds so that they can be played? Thanks -- Noah Silverman UCLA Department of Statistics 8208 Math Sciences Building Los Angeles, CA 90095 [[alternative HTML version deleted]]

Hello, I was just assigned to perform a cost effectiveness study in healthcare. We are studying the cost effectiveness of a proposed diagnostic vs. current screening procedures. One of the team members suggest a commercial software package called "TreeAge Pro". Looking at the description, it appears to be a nice GUI to some very simple models that could be easily constructed in R.

Hi, Next challenge today. I have a script that I call within R: source("foo.R") When it finishes, I get the dreaded output: "There were 50 or more warnings (use warnings() to see the first 50)" So, I type warnings() and get a nice list. (Same error repeatedly, so probably something I'm using in a loop.) The difficult part is I have no idea *where* the warning is

Hi, I want to store the output of my program to a file. However, With subsequent runs of my code, I'd like to append to the same log file. Currently, I'm using: outfile <- file("log.txt", open="w") cat(results, file=outfile) This works, but will overwrite the log file each time. Is there a way to open a file and have R append to the end? Thanks! -- Noah

Hello, I need to design a fairly simple front-end for someone to use an R script system that I've built. My thought was to just use the text based menus available in the base R package, perhaps in some kind of loop. How have other people done this? Any "best practices" that you can recommend? Thanks! -- Noah Silverman UCLA Department of Statistics 8117 Math Sciences Building

I have a bunch of data sets that were created for the libsvm tool. They are in "colon separated sparse format". i.e. 1 5:1 27:3 345:10 Is a row with the label of "1" and only has values in columns 5, 27, and 345. I want to read these into a data.frame in R. Is there a simple way to do this? -- Noah Silverman, M.S. UCLA Department of Statistics 8117 Math Sciences

Hello, I'm attempting to build a package using R 2.15.0 on OS X I am getting a generic failure when performing a cran type check on the package. Even with a very simple test package, it still fails int he same place. Example: In R: rm(list=ls()) foo <- function(x){print(x)} package.skeleton(name="foo") Then, at the command line: R CMD build foo R CMD check --as-cran

Hi, Looking at a large data set with many factors. I would like to expand each factor variable into multiple new variables for each level. (0,1) coding. My first though was just to code a big nasty loop, to take each level and cbind a column onto my data set. But, that seems painful. There must be a better way. Is there an "easy" way to do this in R? (Note, I don't want to

In the book, "Regression Modeling Strategies", Frank Harrell uses the function rcs() often. The current version or R and Hmisc library don't appear to have this function. What is an appropriate substitute? Thank You -- Noah Silverman UCLA Department of Statistics 8208 Math Sciences Building Los Angeles, CA 90095 [[alternative HTML version deleted]]

Hi, I have function that I want to optimize. Am playing with the optim() function in R Two issues: 1) I can't seem to get it to work with a function that takes multiple inputs. Dummy Example: myFunc <- function(A,B,D,D){ # Do stuff return E } > myFunc(1,2,3,4) [1] 12 # works fine from command line > optim( par=c(1,2,3,4), fn=myFunc) Error in A+B : 'B' is missing

Hi, I have a very large data set stored as an xts object. xts is very nice about showing row labels as "human readable" dates and times. I want the actual epoch values that are stored internally. The only way I can find to access them is one-at-a-time using the internal function: xcoredata() Calling this in an entire column, the "R" way doesn't work. It will only

Hi, I have several data structures (xts structures). I then have a list of the names of those objects. I'd like to access the object by name. For example: foo1 <- as.xts(....) foo2 <- as.xts(...) foo3 <- as.xts(...) structs <- c("foo1", "foo2", "foo3") for (thisOne in structs){ print(thisOne$colA) } The above fails. Clearly I'm missing a

Hi, When using the glmnet() function of the package glmnet, A series of coefficients is returned for a list of descending lambda values. I am unable to locate anything in the documentation that explains HOW this choice of lambda series is made. (There is documentation about how to choose my own, but I want to understand how the authors are doing it) Any ideas? -- Noah Silverman UCLA