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# Questions tagged [sampling]

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82 views

### How to find a fit for the following data?

Consider the following function: ...
• 5,851
2 votes
1 answer
95 views

### Fast sampling from Fermi-Dirac distribution under specific conditions

This question is a continuation of the following one. Let us assume a Fermi-Dirac (FD) distribution (times $p^{2}$): ...
• 5,851
1 vote
1 answer
116 views

### How to quickly sample from the following distributions

Consider the following distributions: ...
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1 vote
1 answer
90 views

### How to compile the following code (sampling from a distribution)?

Consider the following code: ...
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0 votes
0 answers
51 views

### How to quickly sample points according to the given distribution?

Consider the following points sampler: ...
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0 votes
1 answer
81 views

### Resampling the points with a constraint [closed]

I have a list of npts elements energies obeying some arbitrary distribution. By performing some operation many times, it would ...
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2 votes
0 answers
54 views

### Why RandomSample fails and how to fix this?

Consider the following sampling: weights = 10^RandomReal[{-13, Log10[35]}, 499500]; vals = Range[Length[weights]]; randomvals = RandomSample[weights -> vals]; ...
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1 answer
77 views

### How to select non-repeating pair of numbers?

Consider the following combinations of integers comb, where the integers range from 1 to n ...
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0 answers
129 views

### How to quickly generate the values satisfying the given condition?

Consider some domains in variables th, z and some condition cond defining the domain of a ...
• 5,851
4 votes
1 answer
221 views

### How to quickly sample points from the given PDF data?

Consider some data (distr.dat). It is a tabulated PDF: x, y, z, PDF[x,y,z], where x is some parameter (and the integral of ...
• 5,851
1 vote
1 answer
119 views

### Pick random value based on list of probabilities

I'm pretty sure this must have been asked before, but I can not find the duplicate. Given a list of values with their probabilities ...
• 1,419
1 vote
2 answers
149 views

### How to sample from a MultinormalDistribution with a positive semidefinite covariance matrix?

I'm trying to sample from a Gaussian process (GP) following these tutorials: https://peterroelants.github.io/posts/gaussian-process-tutorial/#Sampling-from-prior https://stephens999.github.io/...
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2 votes
3 answers
103 views

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0 votes
2 answers
45 views

### Cannot use RandomSample to get a sample bigger than the original [closed]

I have a sample of 300 elements and I need a random vector of size 100000 which consists of random repetitions of the elements of the 300-element sample I have tried the following ...
• 233
4 votes
1 answer
73 views

### Speeding up RandomVariate with custom probability distribution

I have the defined a custom distribution, which is a Gaussian where the exponent can be any real n greater than 0 (set to actually be >0.5 in use), i.e. ...
• 115
6 votes
4 answers
809 views

### Finding the periodicity (or wavelength) in approximately periodic data irregularly sampled

I have irregularly sampled data that looks as in the picture. Is there a function in Mathematica that allows me to find an approximate or average period or wavelength? I know beforehand that the data ...
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0 votes
1 answer
82 views

### Is there a difference between generating and loading data?

EDIT-1 This is a minimal example where an error occurs after 44538 samples generated in d1 upon importing as d2. Note that if <...
• 233
4 votes
2 answers
208 views

### Is there a way to generate a data-driven Monte Carlo sample from a histogram?

I have a vector with 50 elements. These are values of a random variable. I have represented the data as Histogram[RandomVariable1Histogram]. However, I need to ...
• 233
4 votes
1 answer
152 views

### Reverse engineer visualizations to compactly extract underlying data

TL;DR How to implement in mathematica a tool such as WebPlotDigitizer by Ankit Rohatgi which would allow us to trace automatically curves from either (randomly ordered) data or imported images. ...
• 23k
4 votes
2 answers
203 views

### Smart under-sampling of a large list of data points

I have dielectric functions of materials as lists of value pairs {{x1, y1}, {x2, y2}, ...} and unfortunately some of them are quite long, which is a bother in ...
1 vote
0 answers
60 views

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1 vote
1 answer
65 views

### Select a subsequence of a sequence according to tosses of a biased coin

I have a sequence, from which I would like to select a subsequence, each term of the original sequence being included in the subsequence with probability $p$, independently of the other terms. That is,...
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1 vote
2 answers
242 views

### Evaluate function at "good" points used by Plot in numerical problems

Plot function with option Mesh->All shows how mathematica evaluates function to make it most optimal for plotting. I'd like to evaluate some physical function in ...
0 votes
2 answers
80 views

### How to get a list of exponentially distributed points sampled in a range

I want to get 256 points exponentially sampled in a range, and then get its histogram. If I plot PDF, I get the following: ...
• 157
3 votes
4 answers
344 views

### Sampling Implicit functions

Consider an implicit function like f ...
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2 votes
1 answer
140 views

### How to extract colors from ColorsNear?

Is there any way to get a discrete list of samples from the ColorsNear function? I have tried ...
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0 votes
1 answer
177 views

### Sampling two integer lists of given sizes from a distribution that have equal sums

(This question emerged from discussions in this post.) Context and code sample: I am trying to figure out if there is a way to generate two $a$ and $b,$ comprised of $n_a$ and $n_b$ integers which ...
1 vote
2 answers
78 views

### Sampling an inequality over multi-dimensional space

Let's say I have two functions $f(x,y,z), g(x,y,z)$. I would like to know the probability that $f(x,y,z) < g(x,y,z)$ over some defined, numerical ranges of $x, y, z$. Any thoughts on how to do it ...
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8 votes
2 answers
337 views

### Plot, sampling, and why it does not display for some ranges

The following gives an empty plot on V12 under Windows 10: ...
• 146k
5 votes
2 answers
497 views

### Why does plot not show where Piecewise function is not zero?

From my user point view this looks like bug. But I am not an expert. f[x_?NumericQ]:=Piecewise[{{1,x==1},{0,True}}]; Plot[f[x],{x,0,1}] Does not show ...
• 146k
1 vote
1 answer
188 views

### Random sampling of a discrete distribution in NetGraph

Within a NetGraph I would like to use the output of a softmax layer, interpreted as a probability distribution, to sample a "next token". Since this is done inside an RNN structure, I cannot do this ...
1 vote
2 answers
352 views

### Multiple unique random samples?

I'm trying to produce $n$ random samples from a list, but not all samples, and I'd like the samples to not repeat in the same execution of the command. If I'm not mistaken, something like ...
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2 votes
4 answers
744 views

### How to generate a matrix with certain conditions

I want to generate a $n \times n$ matrix. I want the diagonal entries to be all 0 I want a random choice of matrix elements with 0 or 1. The probability of having a 1 as a matrix element is $1/m$ and ...
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0 votes
1 answer
226 views

### How do I extract data points from an audio plot at a constant spaced time interval?

AudioPlot[Audio[File["Downloads/1_mp3.wav"]]] data = Cases[AudioPlot[Audio[File["Downloads/1_mp3.wav"]]], Line[x_] :> x, Infinity] This code can extract data ...
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1 vote
2 answers
192 views

### Sampling data from numerical values of density distribution of nucleons

How could i sample my data which follows distribution if i have only numerical values of density distribution as an example data attached as in picture I tried but do not know how to do it. The data:...
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0 votes
1 answer
54 views

### ProbabilityDistribution fails for square root

I would like to sampling data from a distribution Sqrt[x^2 + y^2]. I used the code as follows: ...
• 1,131
0 votes
1 answer
114 views

### Speeding up Module

I am working on the Ising 2D model in Mathematica and this is currently my Metropolis sampling function: ...
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4 votes
2 answers
184 views

### Filtering data with timestamps

How to apply filter to data that was sampled in certain moments of time? Examples from documentation deal only with uniformly sampled data: ...
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0 votes
3 answers
136 views

### Sample the data with equal step size

I have the data below. I would like to sample with equal step size. For simplicity lets try unit step size. Here is the desired result. Find the first time exceed the unit time step, and take lower ...
• 10.9k
5 votes
2 answers
240 views

### Random sample of big big numbers

Consider the following piece of code: m = 2; n = 6; samplesize = 1000; totalsize = 2^(n^m); numbersample = 2 RandomSample[Range[totalsize/2], samplesize]; With ...
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5 votes
3 answers
405 views

### Sample over a matrix

Assume I have a matrix. ...
• 10.9k
2 votes
1 answer
87 views

### Looking for an estimator for non-linear statistics

Goal We sample $n$ individuals with replacement and measure their trait values $x_i$ for all individual $i$. The variable $x$ is bounded [0,1]. Let $\mu$ be the ...
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0 votes
0 answers
89 views

### Problems with sampling

Let $t\ge 0$ and let $f_{s}(t)$ be the sampled version of $f(t)$. If $$f(t)=\begin{cases}\int_{0}^{t}\exp\left(-\frac{1}{1-s^{2}}\right)\,ds,&|s|<1, \\ 0,&\text{otherwise}.\end{cases}$$ I ...
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26 votes
4 answers
3k views

### How to sample points randomly below a curve? [duplicate]

How can I randomly select 1000 points uniformly from the shaded area below the plotted curve? Plot[1/π Cos[θ]^2, {θ, 0, 2 π}, Filling -> Bottom]
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5 votes
2 answers
326 views

### Generate multiple integer variables with constant sum

I have asked similar question three day ago[The old question]. it was incorrectly marked as duplicated. This time I make this question more general and closer to reality. I want to build a model of N ...
• 594
38 votes
4 answers
2k views

### How to implement the sample-point process like the built-ins of Mathematica?

Consider this: pts = {{0, 0}, {1, 1}, {2, -1}, {3, 0}, {4, -2}, {5, 1}}; f = BSplineFunction[pts] I can use ParametricPlot to ...
• 625
7 votes
1 answer
379 views

### Draw from a given list according to empirical distribution

I have two lists, where each time I have age-income vectors. Given the distribution of age in the first list, I would like to draw a sample with the similar distribution of age from the second list (...
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23 votes
2 answers
2k views

### How to obtain adaptive sampling as in Plot function?

Adaptive sampling in Plot function can capture the oscillation of a function with very few points. How can I get a similar sequence of point pairs without using <...
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0 votes
1 answer
343 views

### Sampling Points Between Two Functions and Plotting Sample Points? (I have partial code) [duplicate]

I want to sample random points between $Cos(x)$ and $Sin(x)$ on $0 \le x\le \frac \pi4$ I was able to do graph the function here in Mathematica. I would like to count, and then plot points between ...
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2 votes
0 answers
1k views

### Draw sample functions from Gaussian Process prior [closed]

Previously, I have written implementation codes of Gaussian Process regression in Python and Matlab. However, for better interaction and visualisation, I am currently working on implementation in ...
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