pip-services3-commons-node/src/random/RandomFloat.ts

Portable abstractions and patterns for Pip.Services in Node.js

/** @module random */

/**
 * Random generator for float values.
 * 
 * ### Example ###
 * 
 *     let value1 = RandomFloat.nextFloat(5, 10);     // Possible result: 7.3
 *     let value2 = RandomFloat.nextFloat(10);        // Possible result: 3.7
 *     let value3 = RandomFloat.updateFloat(10, 3);   // Possible result: 9.2
 */
export class RandomFloat {
   
    /**
     * Generates a float in the range ['min', 'max']. If 'max' is omitted, then the range will be set to [0, 'min'].
     * 
     * @param min   minimum value of the float that will be generated. 
     *              If 'max' is omitted, then 'max' is set to 'min' and 'min' is set to 0.
     * @param max   (optional) maximum value of the float that will be generated. Defaults to 'min' if omitted.
     * @returns     generated random float value.
     */
    public static nextFloat(min: number, max: number = null): number {
        if (max == null) {
            max = min;
            min = 0;
        }

        if (max - min <= 0)
            return min;

        return min + Math.random() * (max - min);
    }

    /**
     * Updates (drifts) a float value within specified range defined
     * 
     * @param value     a float value to drift.
     * @param range     (optional) a range. Default: 10% of the value
     */
    public static updateFloat(value: number, range: number = null): number {
        if (range == null) range = 0;
        range = range == 0 ? 0.1 * value : range;
        let minValue = value - range;
        let maxValue = value + range;
        return RandomFloat.nextFloat(minValue, maxValue);
    }
}