apply

I want to use the apply function on a dataframe, but only apply the function to the last 5 columns. B<- by(wifi,(wifi$Room),FUN=function(y){apply(y, 2, A)}) This applies A to all the columns of y B<- by(wifi,(wifi$Room),FUN=function(y){apply(y[4:9], 2, A)}) This applies A only to columns 4-9 of y, but the total return of B strips off the first 3 columns... I still want those, I just don't want A applied to them. wifi[,1:3]+B also does not do what I expected/wanted. Using an example data.frame and example function (just +1 to all values) A <- function(x) x + 1 wifi <- data.frame(replicate(9,1:4

This question already has an answer here: Use of .apply() with 'new' operator. Is this possible? 35 answers How could I generalise the function below to take N arguments? (Using call or apply?) Is there a programmatic way to apply arguments to 'new'? I don't want the constructor to be treated like a plain function. /** * This higher level function takes a constructor and arguments * and returns a function, which when called will return the * lazily constructed value. * * All the arguments, except the first are pased to the constructor. * * @param {Function} constructor */ function conthunktor

This question already has an answer here: Why apply() returns a transposed xts matrix? 1 answer Apologies, I just realised that this has already been answered here . This should be pretty basic but I do not really understand why it is happening. Can someone help? This is the simple code with the example 'data': applyDirichletPrior <- function (row_vector) { row_vector_added <- row_vector + min (row_vector) row_vector_result <- row_vector_added / sum(row_vector_added) } data <- matrix(c(1,2,3,4,5,6,7,8), nrow=2, ncol=4) applied <- apply(data, 1, function(x) applyDirichletPrior(x)) The output is

I have the following data: x1 x2 x3 x4 34 14 45 53 2 8 18 17 34 14 45 20 19 78 21 48 2 8 18 5 In rows 1 and 3; and 2 and 5 the values for columns X1;X2,X3 are equal. How can I output only those 4 rows, with equal numbers? The output should be in the following format: x1 x2 x3 x4 34 14 45 53 34 14 45 20 2 8 18 17 2 8 18 5 Please, ask me questions if something unclear. ADDITIONAL QUESTION: in the output x1 x2 x3 x4 34 14 45 53 34 14 45 20 2 8 18 17 2 8 18 5 find the sum of values in last column: x1 x2 x3 x4 34 14 45 73 2 8 18 22 You can do this with duplicated , which checks for rows being

I am trying to go from a data frame to a list structure in R (and I know technically a data frame is a list). I have a data frame containing reference chemicals and their mechanisms different targets. For example, estrogen is an estrogen receptor agonist. What I would like is to transform the data frame to a list, because I am tired of typing out something like: refchem$chemical_id[refchem$target=="AR" & refchem$mechanism=="Agonist"] every time I need to access the list of specific reference chemicals. I would much rather access the chemicals by: refchem$AR$Agonist I am looking for a general

I can't seem to make apply function access/modify a variable that is declared outside... what gives? x = data.frame(age=c(11,12,13), weight=c(100,105,110)) x testme <- function(df) { i <- 0 apply(df, 1, function(x) { age <- x[1] weight <- x[2] cat(sprintf("age=%d, weight=%d\n", age, weight)) i <- i+1 #this could not access the i variable in outer scope z <- z+1 #this could not access the global variable }) cat(sprintf("i=%d\n", i)) i } z <- 0 y <- testme(x) cat(sprintf("y=%d, z=%d\n", y, z)) Results: age=11, weight=100 age=12, weight=105 age=13, weight=110 i=0 y=0, z=0 Using the <<- operator