go.charczuk.com@v0.0.0-20240327042549-bc490516bd1a/sdk/mathutil/var.go (about)

     1  /*
     2  
     3  Copyright (c) 2023 - Present. Will Charczuk. All rights reserved.
     4  Use of this source code is governed by a MIT license that can be found in the LICENSE file at the root of the repository.
     5  
     6  */
     7  
     8  package mathutil
     9  
    10  // Var finds the variance for both population and sample data
    11  func Var[T Operatable](input []T, sample int) (variance T) {
    12  	if len(input) == 0 {
    13  		return 0
    14  	}
    15  	m := Mean(input)
    16  
    17  	for _, n := range input {
    18  		variance += (T(n) - m) * (T(n) - m)
    19  	}
    20  
    21  	// When getting the mean of the squared differences
    22  	// "sample" will allow us to know if it's a sample
    23  	// or population and wether to subtract by one or not
    24  	variance = variance / T((len(input) - (1 * sample)))
    25  	return
    26  }
    27  
    28  // VarP finds the amount of variance within a population
    29  func VarP[T Operatable](input []T) T {
    30  	return Var(input, 0)
    31  }
    32  
    33  // VarS finds the amount of variance within a sample
    34  func VarS[T Operatable](input []T) T {
    35  	return Var(input, 1)
    36  }