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Hi there, I have data frame with columns ID and Date. There are multiple rows for each ID, but I only want to keep the *first* such row--i.e., the row corresponding to the earliest event. So if I had, say, 1000 rows of 100 IDs doing an average of ten events each, I'd run this trimming procedure and end up with a data frame containing 100 rows (one for each ID), where each row record that

Hi, I'm trying to use R to get eigenvalues and eigenvectors of a matrix whose elements are of the form (2 * lambda), -(lambda + mu), etc. I'd like R to treat this matrix as a numeric matrix without treating lambda and mu as variable names but rather as some sort of atomic quantities (and hence give eigenvectors in terms of mu and/or lambda). MatLab and Mathematica both do this,

Hi there, I'm in the following directory: ~/Documents/Rstuff/diceFiles/dice_1.1 The directory "dice" is in this directory, with all the usual build files (DESCRIPTION, NAMESPACE, etc). I'm trying to run the following command: R CMD check dice (where "dice" is the name of the package I'm checking), and I get the following: * checking package dependencies ...

Hi there, I'm writing a function that calculates the probability of different outcomes of dice rolls (e.g., the sum of the highest three rolls of five six-sided dice). I'm using the "combinations" function from the "gtools" package, which is great: it gives me a matrix with all of the possible combinations (with repetitions allowed). Now I want to count the number