run-length-encoding

I have no idea how to start my assignment. We got to make a Run-length encoding program, for example, the users enters this string: aaaaPPPrrrrr is replaced with 4a3P5r Can someone help me get started with it? Hopefully this will get you started on your assignment: The fundamental idea behind run-length encoding is that consecutively occurring tokens like aaaa can be replaced by a shorter form 4a (meaning "the following four characters are an 'a'"). This type of encoding was used in the early days of computer graphics to save space when storing an image. Back then, video cards supported a

Problem: Given an atomic vector, find the start and end indices of runs in the vector. Example vector with runs: x = rev(rep(6:10, 1:5)) # [1] 10 10 10 10 10 9 9 9 9 8 8 8 7 7 6 Output from rle() : rle(x) # Run Length Encoding # lengths: int [1:5] 5 4 3 2 1 # values : int [1:5] 10 9 8 7 6 Desired output: # start end # 1 1 5 # 2 6 9 # 3 10 12 # 4 13 14 # 5 15 15 The base rle class doesn't appear to provide this functionality, but the class Rle and function rle2 do. However, given how minor the functionality is, sticking to base R seems more sensible than installing and loading additional

I'm very new with MatLab, I have Run Length Encoding code but it seems to not work, can you help me? I have this input : ChainCode = 11012321170701000700000700766666666666665555555544443344444333221322222322 and I want make it into RLE output : (1,2), (0,1), (1,1), (2,1), (3,1), (2,1), (1,2), (7,1), (0,1), (7,1), (0,1), (1,1), (0,3), (7,1), (0,5), (7,1), (0,2), (7,1), (6,13), (5,8), (4,4), (3,2), (4,5), (3,3), (2,2), (1,1), (3,1), (2,5), (3,1), (2,2) This is my code : lengthcode = 1; N = 1; for i = 2:length(ChainCode) if x(i)==x(i-1) N = N + 1; valuecode(N) = x(i); lengthcode(N) = lengthcode(N

This question already has an answer here: Repeat copies of array elements: Run-length decoding in MATLAB 5 answers My question is similar to this one , but I would like to replicate each element according to a count specified in a second array of the same size. An example of this, say I had an array v = [3 1 9 4] , I want to use rep = [2 3 1 5] to replicate the first element 2 times, the second three times, and so on to get [3 3 1 1 1 9 4 4 4 4 4] . So far I'm using a simple loop to get the job done. This is what I started with: vv = []; for i=1:numel(v) vv = [vv repmat(v(i),1,rep(i))]; end I

For clever usage of linear indexing or accumarray , I've sometimes felt the need to generate sequences based on run-length encoding . As there is no built-in function for this, I am asking for the most efficient way to decode a sequence encoded in RLE. Specification: As to make this a fair comparison I would like to set up some specifications for the function: If optional second argument values of same length is specified, the output should be according to those values, otherwise just the values 1:length(runLengths) . Gracefully handle: zeros in runLengths values being a cell array. Output

Looks like an easy task, can't figure out a simpler way. I have an x vector below, and need to create group names for consecutive values. My attempt was using rle , better ideas? # data x <- c(1,1,1,2,2,2,3,2,2,1,1) # make groups rep(paste0("Group_", 1:length(rle(x)$lengths)), rle(x)$lengths) # [1] "Group_1" "Group_1" "Group_1" "Group_2" "Group_2" "Group_2" "Group_3" "Group_4" # [9] "Group_4" "Group_5" "Group_5" Using diff and cumsum : paste0("Group_", cumsum(c(1, diff(x) != 0))) #[1] "Group_1" "Group_1" "Group_1" "Group_2" "Group_2" "Group_2" "Group_3" "Group_4" "Group_4" "Group_5" "Group_5"