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docs: improve README examples of stats/base/dists/triangular namespace #1797

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85 changes: 83 additions & 2 deletions lib/node_modules/@stdlib/stats/base/dists/triangular/README.md
Original file line number Diff line number Diff line change
Expand Up @@ -112,10 +112,91 @@ y = dist.quantile( 1.9 );
<!-- eslint no-undef: "error" -->

```javascript
var objectKeys = require( '@stdlib/utils/keys' );
var triangularRandomFactory = require( '@stdlib/random/base/triangular' ).factory;
var uniformRandomFactory = require( '@stdlib/random/base/uniform' ).factory;
var filledarrayBy = require( '@stdlib/array/filled-by' );
var variance = require( '@stdlib/stats/base/variance' );
var linspace = require( '@stdlib/array/base/linspace' );
var mean = require( '@stdlib/stats/base/mean' );
var abs = require( '@stdlib/math/base/special/abs' );
var triangular = require( '@stdlib/stats/base/dists/triangular' );

console.log( objectKeys( triangular ) );
// Define the parameters of the triangular distribution:
var a = 0.0; // Minimum value
var b = 10.0; // Maximum value
var c = 4.0; // Mode (most likely value)

// Generate an array of x values:
var x = linspace( a, b, 100 );

// Compute the PDF for each x:
var triangularPDF = triangular.pdf.factory( a, b, c );
var pdf = filledarrayBy( x.length, 'float64', triangularPDF );

// Compute the CDF for each x:
var triangularCDF = triangular.cdf.factory( a, b, c );
var cdf = filledarrayBy( x.length, 'float64', triangularCDF );

// Output the PDF and CDF values:
console.log( 'x values:', x );
console.log( 'PDF values:', pdf );
console.log( 'CDF values:', cdf );

// Compute statistical properties:
var theoreticalMean = triangular.mean( a, b, c );
var theoreticalVariance = triangular.variance( a, b, c );
var theoreticalSkewness = triangular.skewness( a, b, c );
var theoreticalKurtosis = triangular.kurtosis( a, b, c );

console.log( 'Theoretical Mean:', theoreticalMean );
console.log( 'Theoretical Variance:', theoreticalVariance );
console.log( 'Skewness:', theoreticalSkewness );
console.log( 'Kurtosis:', theoreticalKurtosis );

// Generate random samples from the triangular distribution:
var rtriangular = triangularRandomFactory( a, b, c );
var n = 1000;
var samples = filledarrayBy( n, 'float64', rtriangular );

// Compute sample mean and variance:
var sampleMean = mean( n, samples, 1 );
var sampleVariance = variance( n, 1, samples, 1 );

console.log( 'Sample Mean:', sampleMean );
console.log( 'Sample Variance:', sampleVariance );

// Compare sample statistics to theoretical values:
console.log( 'Difference in Mean:', abs( theoreticalMean - sampleMean ) );
console.log( 'Difference in Variance:', abs( theoreticalVariance - sampleVariance ) );

// Demonstrate the relationship between the triangular distribution and the sum of uniform distributions, namely that the sum of two independent Uniform(0, 1) random variables follows a Triangular(0, 2, 1) distribution.

// Generate samples by summing two independent Uniform(0, 1) random variables:
var runiform = uniformRandomFactory( 0.0, 1.0 );

function runiformSum() {
return runiform() + runiform();
}
var sumSamples = filledarrayBy( n, 'float64', runiformSum );

// Compute sample mean and variance for the sum:
var sumSampleMean = mean( n, sumSamples, 1 );
var sumSampleVariance = variance( n, 1, sumSamples, 1 );

// Theoretical mean and variance of Triangular(0, 2, 1):
var a2 = 0.0;
var b2 = 2.0;
var c2 = 1.0;

var triMean = triangular.mean( a2, b2, c2 );
var triVariance = triangular.variance( a2, b2, c2 );

console.log( 'Sum Sample Mean:', sumSampleMean );
console.log( 'Sum Sample Variance:', sumSampleVariance );
console.log( 'Theoretical Mean (Sum of Uniforms):', triMean );
console.log( 'Theoretical Variance (Sum of Uniforms):', triVariance );
console.log( 'Difference in Mean:', abs( triMean - sumSampleMean ) );
console.log( 'Difference in Variance:', abs( triVariance - sumSampleVariance ) );
```

</section>
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,88 @@

'use strict';

var objectKeys = require( '@stdlib/utils/keys' );
var triangularRandomFactory = require( '@stdlib/random/base/triangular' ).factory;
var uniformRandomFactory = require( '@stdlib/random/base/uniform' ).factory;
var filledarrayBy = require( '@stdlib/array/filled-by' );
var variance = require( '@stdlib/stats/base/variance' );
var linspace = require( '@stdlib/array/base/linspace' );
var mean = require( '@stdlib/stats/base/mean' );
var abs = require( '@stdlib/math/base/special/abs' );
var triangular = require( './../lib' );

console.log( objectKeys( triangular ) );
// Define the parameters of the triangular distribution:
var a = 0.0; // Minimum value
var b = 10.0; // Maximum value
var c = 4.0; // Mode (most likely value)

// Generate an array of x values:
var x = linspace( a, b, 100 );

// Compute the PDF for each x:
var triangularPDF = triangular.pdf.factory( a, b, c );
var pdf = filledarrayBy( x.length, 'float64', triangularPDF );

// Compute the CDF for each x:
var triangularCDF = triangular.cdf.factory( a, b, c );
var cdf = filledarrayBy( x.length, 'float64', triangularCDF );

// Output the PDF and CDF values:
console.log( 'x values:', x );
console.log( 'PDF values:', pdf );
console.log( 'CDF values:', cdf );

// Compute statistical properties:
var theoreticalMean = triangular.mean( a, b, c );
var theoreticalVariance = triangular.variance( a, b, c );
var theoreticalSkewness = triangular.skewness( a, b, c );
var theoreticalKurtosis = triangular.kurtosis( a, b, c );

console.log( 'Theoretical Mean:', theoreticalMean );
console.log( 'Theoretical Variance:', theoreticalVariance );
console.log( 'Skewness:', theoreticalSkewness );
console.log( 'Kurtosis:', theoreticalKurtosis );

// Generate random samples from the triangular distribution:
var rtriangular = triangularRandomFactory( a, b, c );
var n = 1000;
var samples = filledarrayBy( n, 'float64', rtriangular );

// Compute sample mean and variance:
var sampleMean = mean( n, samples, 1 );
var sampleVariance = variance( n, 1, samples, 1 );

console.log( 'Sample Mean:', sampleMean );
console.log( 'Sample Variance:', sampleVariance );

// Compare sample statistics to theoretical values:
console.log( 'Difference in Mean:', abs( theoreticalMean - sampleMean ) );
console.log( 'Difference in Variance:', abs( theoreticalVariance - sampleVariance ) );

// Demonstrate the relationship between the triangular distribution and the sum of uniform distributions, namely that the sum of two independent Uniform(0, 1) random variables follows a Triangular(0, 2, 1) distribution.

// Generate samples by summing two independent Uniform(0, 1) random variables:
var runiform = uniformRandomFactory( 0.0, 1.0 );

function runiformSum() {
return runiform() + runiform();
}
var sumSamples = filledarrayBy( n, 'float64', runiformSum );

// Compute sample mean and variance for the sum:
var sumSampleMean = mean( n, sumSamples, 1 );
var sumSampleVariance = variance( n, 1, sumSamples, 1 );

// Theoretical mean and variance of Triangular(0, 2, 1):
var a2 = 0.0;
var b2 = 2.0;
var c2 = 1.0;

var triMean = triangular.mean( a2, b2, c2 );
var triVariance = triangular.variance( a2, b2, c2 );

console.log( 'Sum Sample Mean:', sumSampleMean );
console.log( 'Sum Sample Variance:', sumSampleVariance );
console.log( 'Theoretical Mean (Sum of Uniforms):', triMean );
console.log( 'Theoretical Variance (Sum of Uniforms):', triVariance );
console.log( 'Difference in Mean:', abs( triMean - sumSampleMean ) );
console.log( 'Difference in Variance:', abs( triVariance - sumSampleVariance ) );
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