sampling

A common way for sampling/splitting data in R is using sample , e.g., on row numbers. For example: require(data.table) set.seed(1) population <- as.character(1e5:(1e6-1)) # some made up ID names N <- 1e4 # sample size sample1 <- data.table(id = sort(sample(population, N))) # randomly sample N ids test <- sample(N-1, N/2, replace = F) test1 <- sample1[test, .(id)] The problem is that this isn't very robust to changes in the data. For example if we drop just one observation: sample2 <- sample1[-sample(N, 1)] samples 1 and 2 are still all but identical: nrow(merge(sample1, sample2)) [1] 9999 Yet

This question already has answers here : generate random integers between two values with a given probability using R (2 answers) Closed 6 years ago . I need to get out a sample of subjects from a list to assign them as a Control Group for a study which has to have a similar composition of variables. I am trying to do this in R with the sample function but I don´t know how to specify the differetnt probabilities for each variable. Lets say I have a table with the following headers: ID Name Campaign Gender I need a sample of 10 subjects with the following composition of Campaign attributes: D2D

I have difficulty understanding what it means when an rnorm is used as one of the arguments of another rnorm ? (I'll explain more below) For example, below, in the first line of my R code I use an rnorm() and I call this rnorm() : mu . mu consists of 10,000 x . Now, let me put mu itself as the mean argument of a new rnorm() called "distribution". My question is how mu which itself has 10,000 x be used as the mean argument of this new rnorm() called distribution? P.S.: mean argument of any normal distribution can be a single number, and with only ONE single mean, we will have a single, complete

Decoded audio using FFmpeg (function avcodec_decode_audio3) and try to reproduce it through Audiotrack in Android. When playing I hear some growling. No music. On the forums advised that the problem with the samples. Question: how to solve this problem, if it is associated with a mismatch of types of samples? Code decoding: while (av_read_frame(pFormatCtx, &packet)>= 0) { if (aCodecCtx->codec_type == AVMEDIA_TYPE_AUDIO) { int data_size = AVCODEC_MAX_AUDIO_FRAME_SIZE * 2; int size=packet.size; int decoded = 0; while(size > 0) { int len = avcodec_decode_audio3(aCodecCtx, (uint16_t *)

I'm writing some modelling routines in NumPy that need to select cells randomly from a NumPy array and do some processing on them. All cells must be selected without replacement (as in, once a cell has been selected it can't be selected again, but all cells must be selected by the end). I'm transitioning from IDL where I can find a nice way to do this, but I assume that NumPy has a nice way to do this too. What would you suggest? Update: I should have stated that I'm trying to do this on 2D arrays, and therefore get a set of 2D indices back. How about using numpy.random.shuffle or numpy.random

I'm following the Profiling Tutorial here: http://msdn.microsoft.com/en-us/magazine/cc337887.aspx I've tried to profile the project by using CPU sampling. MSDN Results: My Results: I'm expecting to see System.Drawing.Bitmap.SetPixel instead of the [System.Drawing.ni.dll] . As recommended by this post , I have: Clicked the "Show All Code" link Disabled "Just My Code" Checked "Microsoft Symbol Serves" in Tools > Options > Debugging > Symbols, restarted visual studio and ran the report again. Output (after following above steps): Failed to load symbols for C:\Windows\assembly\NativeImages_v2.0