framework/base/Application.php
public function getVendorPath()
    {
        if ($this->_vendorPath === null) {
            $this->setVendorPath($this->getBasePath() . DIRECTORY_SEPARATOR . 'vendor');
        }

        return $this->_vendorPath;
    }
public function getVendorPath()
    {
        if ($this->_vendorPath === null) {
            $this->setVendorPath($this->getBasePath() . DIRECTORY_SEPARATOR . 'vendor');
        }

        return $this->_vendorPath;
    }
Returns the directory that stores vendor files.
@return string the directory that stores vendor files.
Defaults to "vendor" directory under [[basePath]].