code: def test_default_2components():
      pca = PCA(n_components=2)
      res = pca.fit(X_std).transform(X_std)
      assert res.shape[1] == 2
  
file_path: mlxtend/mlxtend/feature_extraction/tests/test_principal_component_analysis.py
imports: import numpy
  from numpy.testing import assert_allclose, assert_almost_equal
  from mlxtend.data import iris_data
  from mlxtend.feature_extraction import PrincipalComponentAnalysis
  from mlxtend.preprocessing import standardize
  from mlxtend.utils import assert_raises
label_desc: Use image node_id 3 for calling a global function with example usage: test_default_2components() without return types