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Calculate the median value of a sorted strided array.
npm install @stdlib/stats-base-mediansorted
Alternatively,
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var mediansorted = require( '@stdlib/stats-base-mediansorted' );
Computes the median value of a sorted strided array x
.
var x = [ 1.0, 2.0, 3.0 ];
var v = mediansorted( x.length, x, 1 );
// returns 2.0
x = [ 3.0, 2.0, 1.0 ];
v = mediansorted( x.length, x, 1 );
// returns 2.0
The function has the following parameters:
- N: number of indexed elements.
- x: input
Array
ortyped array
. - stride: index increment for
x
.
The N
and stride
parameters determine which elements in x
are accessed at runtime. For example, to compute the median value of every other element in x
,
var floor = require( '@stdlib/math-base-special-floor' );
var x = [ 1.0, 2.0, 2.0, -7.0, 3.0, 3.0, 4.0, 2.0 ];
var N = floor( x.length / 2 );
var v = mediansorted( N, x, 2 );
// returns 2.5
Note that indexing is relative to the first index. To introduce an offset, use typed array
views.
var Float64Array = require( '@stdlib/array-float64' );
var floor = require( '@stdlib/math-base-special-floor' );
var x0 = new Float64Array( [ 2.0, 1.0, 2.0, 2.0, -2.0, 2.0, 3.0, 4.0 ] );
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var N = floor( x0.length / 2 );
var v = mediansorted( N, x1, 2 );
// returns 2.0
Computes the median value of a sorted strided array using alternative indexing semantics.
var x = [ 1.0, 2.0, 3.0 ];
var v = mediansorted.ndarray( x.length, x, 1, 0 );
// returns 2.0
The function has the following additional parameters:
- offset: starting index for
x
.
While typed array
views mandate a view offset based on the underlying buffer
, the offset
parameter supports indexing semantics based on a starting index. For example, to calculate the median value for every other value in x
starting from the second value
var floor = require( '@stdlib/math-base-special-floor' );
var x = [ 2.0, 1.0, 2.0, 2.0, -2.0, 2.0, 3.0, 4.0 ];
var N = floor( x.length / 2 );
var v = mediansorted.ndarray( N, x, 2, 1 );
// returns 2.0
- If
N <= 0
, both functions returnNaN
. - The input strided array must be sorted in either strictly ascending or descending order.
var Float64Array = require( '@stdlib/array-float64' );
var mediansorted = require( '@stdlib/stats-base-mediansorted' );
var x;
var i;
x = new Float64Array( 10 );
for ( i = 0; i < x.length; i++ ) {
x[ i ] = i - 5.0;
}
console.log( x );
var v = mediansorted( x.length, x, 1 );
console.log( v );
@stdlib/stats-base/dmediansorted
: calculate the median value of a sorted double-precision floating-point strided array.@stdlib/stats-base/mean
: calculate the arithmetic mean of a strided array.@stdlib/stats-base/smediansorted
: calculate the median value of a sorted single-precision floating-point strided array.
This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
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