pocketmine\level\generator\populator\TallGrass::setRandomAmount PHP Method

    public function setRandomAmount($amount)
    {
        $this->randomAmount = $amount;
    }

 public function init(GenerationChunkManager $level, Random $random)
 {
     $this->level = $level;
     $this->random = $random;
     $this->random->setSeed($this->level->getSeed());
     $this->noiseHills = new Simplex($this->random, 3, 0.1, 12);
     $this->noiseBase = new Simplex($this->random, 16, 0.6, 16);
     $ores = new Ore();
     $ores->setOreTypes([new OreType(new CoalOre(), 20, 16, 0, 128), new OreType(new IronOre(), 20, 8, 0, 64), new OreType(new RedstoneOre(), 8, 7, 0, 16), new OreType(new LapisOre(), 1, 6, 0, 32), new OreType(new GoldOre(), 2, 8, 0, 32), new OreType(new DiamondOre(), 1, 7, 0, 16), new OreType(new Dirt(), 20, 32, 0, 128), new OreType(new Gravel(), 10, 16, 0, 128)]);
     $this->populators[] = $ores;
     $trees = new Tree();
     $trees->setBaseAmount(1);
     $trees->setRandomAmount(1);
     $this->populators[] = $trees;
     $tallGrass = new TallGrass();
     $tallGrass->setBaseAmount(5);
     $tallGrass->setRandomAmount(0);
     $this->populators[] = $tallGrass;
 }