indices

Suppose I have the sequence: x = c( 1, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0) Is there an elegant way in R to return the start and stop indices of each sequence of 1s? The answer should be a 2 column array with nRows = number of sequences of 1s: startIndx = [ 1, 5, 7 ] stopIndex = [ 2, 5, 9 ] Thanks. BSL Assuming your vector consists of 0 and 1 values: which(diff(c(0L, x)) == 1L) #[1] 1 5 7 which(diff(c(x, 0L)) == -1L) #[1] 2 5 9 Otherwise you'd need something like x <- x == 1L first. Elegant way is y <- which(x==1) startIndx <- y[!(y-1) %in% y] stopIndex <- y[!(y+1) %in% y] rbind(startIndx, stopIndex)

If you wanted to render a large landscape with thousands of polygons in the viewing frustum at a time as well as the user's viewpoint changing constantly, is it practical to use VAOs or VBOs? I mean, every time the player's position or camera rotation changed, you would have to recompute the vertex data in order to properly cull any vertices or scenes which are no longer seen in order to keep a good FPS count. But in doing this, your FPS count would go down because you are, well, repacking all the buffers constantly. So is it still beneficial to use these two methods over immediate mode? My

I'd like to have arrays that start from say an index of 4 and go to 9. I'm not interested in creating memory space for < 4, so how is best to proceed? My 2D code is as follows: arr = [[ 0 for row in range(2)] for col in range(1, 129)] >>> arr[0][0] = 1 >>> arr[128][0] = 1 Traceback (most recent call last): File "<stdin>", line 1, in ? IndexError: list index out of range >>> arr[127][0] = 1 How can selectively just use the specific range i.e. where the last index runs from 1 to 128 inclusive not 0 to 127. This maybe obvious, but is there a way to do this? Thanks for the suggestion for dicts, I

My input was a csv file which was imported to postgresqldb .Later i am building a cnn using keras.My code below gives the following error "IndexError: too many indices for array". I am quite new to machine learning so I do not have any idea about how to solve this. Any suggestions? X = dataframe1[['Feature1','Feature2','Feature3','Feature4','Feature5','Feature6','Feature7','Feature8','Feature9','Feature10','Feature11\1','Feature12','Feature13','Feature14']] Y=result[['label']] # evaluate model with standardized dataset results = cross_val_score(estimator, X, Y, cv=kfold) print("Results: %.2f%%

I was just wondering for a while now what exactly "offsets" and "indices / index" are. Offsets are e.g. mentioned in https://github.com/mrdoob/three.js/blob/dev/src/core/BufferGeometry.js and indices were mentioned in IndexedGeometry, however I can't currently find it anymore in the dev tree. Although indices seem rather obvious and although I could dive into the code to figure out some maybe-correct answer for myself I'd love to hear an "official" statement :) Thanks! There are two ways to defining geometries: Non-Indexed "vertices": [ 0, 1, 2, 3, 4, 5, 6, 7, 8, ... ], "normals": [ 0, 1, 2, 3

to get right down to it, I'm trying to iterate through a list of coordinate pairs in python and delete all cases where one of the coordinates is negative. For example: in the array: map = [[-1, 2], [5, -3], [2, 3], [1, -1], [7, 1]] I want to remove all the pairs in which either coordinate is < 0, leaving: map = [[2, 3], [7, 1]] My problem is that python lists cannot have any gaps, so if I loop like this: i = 0 for pair in map: for coord in pair: if coord < 0: del map[i] i += 1 All the indices shift when the element is deleted, messing up the iteration and causing all sorts of problems. I've

I'm trying to draw a terrain with GL_TRIANGLE_STRIP and glDrawElements but I'm having a really hard time understanding the indices thing behind glDrawElements ... Here's what I have so far: void Terrain::GenerateVertexBufferObjects(float ox, float oy, float oz) { float startWidth, startLength, *vArray; int vCount, vIndex = -1; // width = length = 256 startWidth = (width / 2.0f) - width; startLength = (length / 2.0f) - length; vCount = 3 * width * length; vArray = new float[vCount]; for(int z = 0; z < length; z++) { // vIndex == vIndex + width * 3 || width * 3 = 256 * 3 = 768 for(int x = 0; x <