framework/base/Application.php
public function setVendorPath($path)
    {
        $this->_vendorPath = Yii::getAlias($path);
        Yii::setAlias('@vendor', $this->_vendorPath);
        Yii::setAlias('@bower', $this->_vendorPath . DIRECTORY_SEPARATOR . 'bower');
        Yii::setAlias('@npm', $this->_vendorPath . DIRECTORY_SEPARATOR . 'npm');
    }
public function setVendorPath($path)
    {
        $this->_vendorPath = Yii::getAlias($path);
        Yii::setAlias('@vendor', $this->_vendorPath);
        Yii::setAlias('@bower', $this->_vendorPath . DIRECTORY_SEPARATOR . 'bower');
        Yii::setAlias('@npm', $this->_vendorPath . DIRECTORY_SEPARATOR . 'npm');
    }
Sets the directory that stores vendor files.
@param string $path the directory that stores vendor files.