FAQ Database Discussion Community


Sampling on factor in R

r,data.frame,sampling
I have a dataset of 1000 rows with the following structure: device geslacht leeftijd type1 type2 1 mob 0 53 C 3 2 tab 1 64 G 7 3 pc 1 50 G 7 4 tab 0 75 C 3 5 mob 1 54 G 7 6 pc 1 58...

Ignoring samples in Gibbs sampling

python,sampling,mcmc
import random,math def gibbs(N=50000,thin=1000): x=0 y=0 print "Iter x y" for i in range(N): for j in range(thin): x=random.gammavariate(3,1.0/(y*y+4)) y=random.gauss(1.0/(x+1),1.0/math.sqrt(2*x+2)) print i,x,y gibbs() The above python code is the Gibbs Sampling and the following line confuses me. for j in range(thin): What is the significance of that additional inner loop?...

Estimating change of a cyclic boolean variable

time-series,sampling,measurement,probability-theory
We have a boolean variable X which is either true or false and alternates at each time step with a probability p. I.e. if p is 0.2, X would alternate once every 5 time steps on average. We also have a time line and observations of the value of this...

Matlab Distribution Sampling

matlab,distribution,sampling,random-sample
How can I create a vector x in Matlab that has values between 0.8 and 1.2, randomly sampled from a: 1. Uniform 2. Normal distribution? There are a lot of functions dealing with distributions, but I'm having trouble using them properly....

Splitting an audio file in Matlab

matlab,audio,frequency,sampling
I'm trying to split an audio file into 30 millisecond disjoint intervals using Matlab. I have the following code at the moment: clear all close all % load the audio file and get its sampling rate [y, fs] = audioread('JFK_ES156.wav'); for m = 1 : 6000 [t(m), fs] = audioread('JFK_ES156.wav',...

Randomly generate a subset data based on probabilities

r,probability,sampling
This is about the resampling questions. I want to generate a species list fro a random sample of n individuals based on the species probabilities. For example: there are 3 species c("sp.1", "sp.2", "sp.3"),and their abundance is c(1,2,3). I want to how the species list if i randomly pick up...

Matching vector values by records in a data frame in R

r,sampling
I have a vector of values r as follows: r<-c(1,3,4,6,7) and a data frame df with 20 records and two columns: id<-c(1,2,3,4,5,6,7,8,9,10,11,12,13,1,4,15,16,17,18,19,20) freq<-c(1,3,2,4,5,6,6,7,8,3,3,1,6,9,9,1,1,4,3,7,7) df<-data.frame(id,freq) Using the r vector I need to extract a sample of records (in the form of a new data frame) from df in a way that...

Selection without replacement - by mutating the list

python,algorithm,sampling
I am looking for the efficient function in Python that does sample selection without replacement, but by actually mutating the original list. That is, alternative to this: random.sample(population, k) that removes the elements from the original list as the sample is selected. List can be millions items large, and there...

Sampling distribution using R

r,sampling
I really need helps to figure out: Suppose we are testing H0: µ = 5 against H1: µ < 5 for a normal population with σ = 1. A random sample of size n = 9 is available from this population. The z test is used with α = 0.05....

Matlab audioread doubles instead of singles

matlab,audio,reshape,sampling
I have the following code at the moment: [y,fs] = audioread('some_audio_file.wav'); y is a <8131546 x 2 double>. Why is that? How come the samples are not a 1 x 8131546? Also when I reshape y to get columns of 30 milliseconds I get a <1324 x 6146 double>? Can...

Binomial Sample Size with r [closed]

r,sampling
I would like to know if there is any package and how to use it about sample size calculation for binomial distribution. I have to sample fruits in three fields and I have to count the number of defects. I would like to know how many fruits i have to...

Android: startRecording() called on an uninitialized AudioRecord when SAMPLERATE set to 44100

java,android,sampling,audiorecord
I get an error, when I set the sampling rate to 44100 for the AudioRecord object. When it's 22050 it works fine. 02-16 10:45:45.099 24021-24021/com.vlad.jackcomms E/AudioRecord﹕ frameCount 1024 < minFrameCount 1792 02-16 10:45:45.099 24021-24021/com.vlad.jackcomms E/AudioRecord-JNI﹕ Error creating AudioRecord instance: initialization check failed. 02-16 10:45:45.099 24021-24021/com.vlad.jackcomms E/android.media.AudioRecord﹕ Error code -20 when...

How to Sample Adobe Analytics (Omniture) Data

adobe,sampling,adobe-analytics
I can't find anything on the web about how to sample Adobe Analytics data? I need to integrate Adobe Analytics into a new website with a ton of traffic so the stakeholders want to sample the data to avoid exorbitant server calls. I'm using DTM but not sure if that...

Sample a random number following a distribution between two values

matlab,random,distribution,gaussian,sampling
I would like to create a gaussian curve between two values (which is the end point of two different calculations). I am aware that i require a bit more background info, but i wish to play with the result. So let us assume what is not known, the values in...

matplotlib argrelmax doesn't find all maxes

python,scipy,sampling
I have a project where I'm sampling analog data and attempting to analyze with matplotlib. Currently, my analog data source is a potentiometer hooked up to a microcontroller, but that's not really relevant to the issue. Here's my code arrayFront = RunningMean(array(dataFront), 15) arrayRear = RunningMean(array(dataRear), 15) x = linspace(0,...

Using camera shutter to trigger MPU6050 on raspberry pi

raspberry-pi,sampling,i2c,gpio,inertial-navigation
I've connected DSLR to RPi by GPIO; and MPU6050 to RPi using I2C. I'm trying to record the gyro and accelerometer data in a small time window (typically less than 50ms) when I press camera shutter button. My desired sampling rate is somewhere in between 500Hz to 1000Hz. And I...