similar to: a question about box counting

Hi, the function outer can not apply a constant function as in the last line of the following example: > xg <- 1:4 > yg <- 1:4 > fxyg <- outer(xg, yg, function(x,y) x*y) > fconstg <- outer(xg, yg, function(x,y) 1.0) Error in outer(xg, yg, function(x, y) 1) : dims [product 16] do not match the length of object [1] Of course there are simpler ways to construct a constant

Hi, I'me trying to write a function that will shuffle a vector. At the moment I'm baically making a vector of randomized indices and then making a new vector from the original one using these random indices. However, is there an alternative (more elegant) method to do this? I tried help.search('shuffle') but it does'nt return anything relevant. Thanks,

Hi, is the following possible - in a given session I make a lot of objects and save when exiting. Usually I note down seperately what each object is about. Is it possible to attach data to any object which would essentially be a short note explaining the meaning of it? Thanks, ------------------------------------------------------------------- Rajarshi Guha <rxg218 at psu.edu>

Hi, I have a factor and I would like to find the most frequent level. I think my current approach is a bit long winded and I was wondering if there was a more elegant way to do it: x <- factor(sample(1:0, 5,replace=TRUE)) levels(x)[ which( as.logical((table(x) == max(table(x)))) == TRUE ) ] (The length of x will always be an odd number, so I wont get a tie in max()) Thanks,

Hi, I am trying to build a series of rlm models. I have my data frame and the models will be built using various coulmns of the data frame. Thus a series of models would be m1 <- rlm(V1 ~ V2 + V3 + V4, data) m2 <- rlm(V1 ~ V2 + V5 + V7, data) m3 <- rlm(V1 ~ V2 + V8 + V9, data) I would like to automate this. Is it possible to use a string in place of the formula? I tried doing: fmla

Hi, this question is probably very obvious but I just cant see where I might be going wrong. I'm using the lm() function to generate a linear model and then make predictions using a different set of data. To generate the model I do (tdata & pdata are matrices of observations and parameters, tdepv, pdepv are response vectors) x <- as.data.frame(tdata) x$tdepv <- tdepv

Hi, I'm trying to parse lines of the form: dan001.hin (0): fingerprint={256, 411, 426, 947, 973, 976} What I need is the sequence of number between {}. I'm using grep as match <- grep("{([0-9,\s]*)}",s,perl=T,value=T) where s is a character vector. But all I get is the whole string s. I tried using regexpr in an attempt to get just the sequence I wanted: match <-

> Or is this a bad idea? I don't like the proposal. I have seen code like the following (in fact, I have written such code, where I had forgotten a function was not vectorized) where the error would have been discovered much later if outer() didn't catch it. > outer(1:3, 11:13, sum) Error in outer(1:3, 11:13, sum) : dims [product 9] do not match the length of object [1]

Hi, I'm trying to translate some Matlab code to R and I'm trying to implement the behavior of Matlab's sort() which when applied to a matrix will sort the columns returning the column sorted matrix as well as a matrix of permuted indices. Doing: > x <- matrix(c(3,4,2,6,3,4,8,7,5), nr=3) > x [,1] [,2] [,3] [1,] 3 6 8 [2,] 4 3 7 [3,] 2 4 5

Hi, I have a rectangular matrix and I need to check whether any columns are identical or not. Currently I'm looping over the columns and checking each column with all the others with identical(). However, as experience has shown me, getting rid of loops is a good idea :) Would anybody have any suggestions as to how I could do this job more efficiently. (It would be nice to know which

Hi, I've written some helper functions which are used by another function (called func()). When func() is sourced I dont want the helper function to be seen in the global namespace (as shown by ls()). Currently what I have done is: func <- function() { helper1 <- function() { ... } helper2 <- function() { ... } # some code } Is there anyway to take the functions

Hi, I have read the previous thread on using references to objects in a function but the solution suggested does'nt seem to be working. basically I have an object x which has an attribute a containing some text. I would like to pass x to a function which will change the attribute a with some new text and have the change visible when the function exits. something like attr(x,'a')

Hi, I have a list in which element is a vector (all of the same length and all numeric). I want to find the mean of the first elements of the vectors, the mean of the second elements of the vectors and so on. Currently I convert the list to a data.frame and apply rowMeans(). But is there a way to to do this directly on the list? I seem to recall a post in which there was such a function (or

Hi, I'm trying to take a set of rows and columns out of a matrix. I hve been using the index aray approach. My overll matrix is X and is 179 x 65. I want to take out 4 columns and 161 rows. Thus I made a 161 x 2 array I and filled it up with the row,col indices. However doing, X[ I ] gives me a vector of the extracted elements. Is there anyway I can coerce this into a 161 x 4 matrix?

Hi I had two questions regarding plots: * Is there are way to save a plot in the form of an object such that it could be displayed/modified later? * I've been using Minitab for some work and I found the burshing capability very handy (it allows me to choose a point on the graph and displays the data associated with it - x,y and other user associated data). I know that this feature is

Hi, is there a function in R that will give me the variances of a predicted values obtained using predict.lm(). If no function is available I would need to calculate them myself - which involves taking the inverse of X'X (' indicating transpose) where X is my model matrix. I know that calculating an inverse directly is not a good idea in general - could anybody suggest a way around

Hi, I'm trying to write a function that will divide a given range of numbers into 3 sets using sample(), without repetition. Currently I'm trying this approach: r <- 1:10 s1 <- sample(r,size=3) Next, I want to remove the selected elements from r and sample() from the remainder. r <- r[ -(r=s1) ] s2 <- sample(r,size=3) When I go to remove the elements contained in s2 from

Hi, I have a matrix of say 1024x1024 and I want to look at it in chunks. That is I'd like to divide into a series of submatrices of order 2x2. | 1 2 3 4 5 6 7 8 ... | | 1 2 3 4 5 6 7 8 ... | | 1 2 3 4 5 6 7 8 ... | | 1 2 3 4 5 6 7 8 ... | ... So the first submatrix would be | 1 2 | | 1 2 | the second one would be | 3 4 | | 3 4 | and so on. That is I want the matrix to be evenly divided

Hi, I have a data.frame with 294 columns and 211 rows. I am calculating correlations between all pairs of columns (excluding column 1) and based on these correlation values I delete one column from any pair that shows a R^2 greater than a cuttoff value. (Rather than directly delete the column all I do is store the column number, and do the deletion later) The code I am using is: ndesc

Hi, I have 3 lists, x, y, z and I'd like to perform a calculation over all the lists simultaneously. If it were a single list I could use lapply, but for more than one list I'm using a for loop. Is there an idiom that would let me use something like lapply, but the function specified to lappy would have access to an element from each list? (In Python, I would have used for a,b,c in