Efficiently adding or removing elements to a vector or list in R?

Question

I\'m implementing an algorithm that involves lots of adding and removing things from sets. In R, this is slow because as far as I know, adding or removing things from a vect

Answer 1

It's hard to say what you want. Maybe you really want stack commands like push and pop. The following isn't that. But it's a fast solution.

Allocate a vector large enough to hold all of your items of the type you need. Set every value to NA. Adding items is simple. Removing items is setting them to NA again. Using the vector is just na.omit(myVec)

myVec <- numeric (maxLength)  # a vector of maximum length

is.na(myVec) <- 1:maxLength   # set every item in myVec to NA

myVec[c(2,6,20)] <- 5         # add some values

na.omit(myVec)

#This will also work if you can initialize all of your values to something that you know you won't need.