Convert Mathematica array text to R array

Mathematica2R.R

#' Turn a string copied from Mathematica into an R array
#'
#'@param text Text representation of a mathematica array.
#'@param drop Logical. If TRUE, 1 and 2 dimensional arrays will be returned as vectors and matrices. 
#'  If FALSE, 1 and 2 dimensional arrays will be returned.
#'
#'@return An array
#'@export
#'@example
#'
#'a1 <- RMatr('{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}')
#'dim(a1)
#'a2 <- RMatr('{{2, 3}, {3, 4}, {4, 5}}')
#'dim(a2)
#'a3 <- RMatr('{{{22, 1111}, {3,3}}, {{3, 3}, {1, 4}}, {{0,4}, {9,5}}}')
#'dim(a3)
#'a4 <- RMatr('{{{{22, 1111}, {3,3}}, {{3, 3}, {1, 4}}, {{0,4}, {9,5}}}}')
#'dim(a4)


RMatr <- function(text, drop = TRUE){
  # Calc number of dimensions
  dim <- nchar(gsub('(^\\{*).*', '\\1', text))

  # Remove whitespace then extra layer of brackets
  text <- gsub(' ', '', text)
  text <- gsub('^\\{|\\}$', '', text)

  # Extract numbers
  nums <- na.omit(as.numeric(strsplit(text, "[^[:digit:]]")[[1]]))

  if(dim == 1) return(nums)

  # Count number of elements at each dimension except last dimension
  dimLengths <- rep(0, dim)
  d <- 0
  for(char in strsplit(text, '')[[1]]){
    if(char == '{'){
      d <- d + 1
    } else if(char == '}'){
      dimLengths[d] <- dimLengths[d] + 1
      d <- d - 1
    }
  }


  # Every element in 2nd dim is counted, but dim length is that divided by number of first dimensions.
  if(dim > 2){
    for(d in 2:(dim - 1)){
      dimLengths[d] <- dimLengths[d] / prod(dimLengths[1:(d - 1)])
    }
  } 

  # Work out last dimension
  dimLengths[length(dimLengths)] <- length(nums)/prod(dimLengths[1:(dim - 1)])


  # Fill array. Have to fill in wrong order then permute dimensions.
  arr <- array(nums, dim = rev(dimLengths))
  arr <- aperm(arr, perm = dim:1)

  if(dim == 2) arr <- as.matrix(arr)
  if(dim == 1) arr <- as.vector(arr)

  return(arr)

}