Alistair Beith

@abeith.bsky.social

25 Followers 56 Following

Research Fellow in Hearing Sciences at University of Nottingham | Speech | Communication | #Rstats

## setup input <- readLines('../data/aoc8.txt') |> sapply(strsplit, split = '') |> do.call(what = rbind) rownames(input) <- NULL antenna_symbols <- input[input != '.'] |> unique() ## part 1 get_nodes <- function(antenna_symbol){ antenna_positions <- which(input == antenna_symbol, arr.ind = TRUE) |> apply(1, \(x) complex(real = x['col'], imaginary = x['row'])) antenna_pairs <- gtools::permutations(length(antenna_positions), 2, antenna_positions) nodes <- apply(antenna_pairs, 1, diff) + antenna_pairs[,2] return(nodes) } check_node <- function(node){ if(Im(node) < 1 | Im(node) > nrow(input)) return(FALSE) if(Re(node) < 1 | Re(node) > ncol(input)) return(FALSE) return(TRUE) } nodes <- sapply(antenna_symbols, get_nodes) |> unlist() nodes <- nodes[sapply(nodes, check_node)] ## part 1 answer nodes |> unique() |> length() ## part 2 get_harmonics <- function(origin, wavelength){ nodes <- c(origin) for(i in seq_len(prod(dim(input)))){ node <- origin + (wavelength * i) if(!check_node(node)) return(nodes) nodes <- c(nodes, node) } stop("This can never happen") } get_node_harmonics <- function(antenna_symbol) { antenna_positions <- which(input == antenna_symbol, arr.ind = TRUE) |> apply(1, \(x) complex(real = x['col'], imaginary = x['row'])) antenna_pairs <- gtools::permutations(length(antenna_positions), 2, antenna_positions) wavelengths <- apply(antenna_pairs, 1, diff) origins <- antenna_pairs[,2] nodes <- purrr::map2(origins, wavelengths, get_harmonics) |> unlist() return(nodes) } harmonics <- sapply(antenna_symbols, get_node_harmonics) |> unlist() |> unique() ## part 2 answer harmonics |> length()
A plot showing the distance matrix between mel-spectrograms of the utterance "Wow, Bob, wow" from the red room scene in the TV show Twin Peaks and the same utterance reversed. A diagonal line from top left to bottom right can be seen indicating the absence of distance between the signal and itself. No similar line from bottom left to top right is visible despite the fact that the phrase is a phonological palindrome.