<?php

namespace MathPHP\SampleData;

/**
 * PlantGrowth data set (Results from an Experiment on Plant Growth)
 *
 * Results from an experiment to compare yields (as measured by dried weight of plants) obtained under a control
 * and two different treatment conditions.
 *
 * 30 observations on 2 variables: weight and group
 * R PlantGrowth
 *
 * Source: Dobson, A. J. (1983) An Introduction to Statistical Modelling. London: Chapman and Hall.
 */
class PlantGrowth
{
    const LABELS = ['weight', 'group'];

    const DATA = [
        [4.17, 'ctrl'],
        [5.58, 'ctrl'],
        [5.18, 'ctrl'],
        [6.11, 'ctrl'],
        [4.50, 'ctrl'],
        [4.61, 'ctrl'],
        [5.17, 'ctrl'],
        [4.53, 'ctrl'],
        [5.33, 'ctrl'],
        [5.14, 'ctrl'],
        [4.81, 'trt1'],
        [4.17, 'trt1'],
        [4.41, 'trt1'],
        [3.59, 'trt1'],
        [5.87, 'trt1'],
        [3.83, 'trt1'],
        [6.03, 'trt1'],
        [4.89, 'trt1'],
        [4.32, 'trt1'],
        [4.69, 'trt1'],
        [6.31, 'trt2'],
        [5.12, 'trt2'],
        [5.54, 'trt2'],
        [5.50, 'trt2'],
        [5.37, 'trt2'],
        [5.29, 'trt2'],
        [4.92, 'trt2'],
        [6.15, 'trt2'],
        [5.80, 'trt2'],
        [5.26, 'trt2'],
    ];

    /**
     * Raw data without labels
     * [[4.17, 'ctrl'], [5.58, 'ctrl'], ... ]
     *
     * @return mixed[]
     */
    public function getData(): array
    {
        return array_values(self::DATA);
    }

    /**
     * Raw data with each observation labeled
     * [['weight' => 4.17, 'group' => 'ctrl'], ['weight' => 5.58, 'group' => 'ctrl'], ... ]
     *
     * @return number[]
     */
    public function getLabeledData(): array
    {
        return array_map(
            function (array $data) {
                return array_combine(self::LABELS, $data);
            },
            self::DATA
        );
    }

    /**
     * Weight observations
     *
     * @return number[]
     */
    public function getWeight(): array
    {
        return array_column(self::DATA, 0);
    }

    /**
     * Group (ctrl, trt1, trt2) observations
     *
     * @return string[]
     */
    public function getGroup(): array
    {
        return array_column(self::DATA, 0);
    }
}