code: def test_pandas_standardize():
      s1 = pd.Series([1, 2, 3, 4, 5, 6], index=(range(6)))
      s2 = pd.Series([10, 9, 8, 7, 6, 5], index=(range(6)))
      df = pd.DataFrame(s1, columns=["s1"])
      df["s2"] = s2
  
      df_out1 = standardize(df, ["s1", "s2"])
      ary_out1 = np.array(
          [
              [-1.46385, 1.46385],
              [-0.87831, 0.87831],
              [-0.29277, 0.29277],
              [0.29277, -0.29277],
              [0.87831, -0.87831],
              [1.46385, -1.46385],
          ]
      )
      np.testing.assert_allclose(df_out1.values, ary_out1, rtol=1e-03)
  
file_path: mlxtend/mlxtend/preprocessing/tests/test__scaling__standardizing.py
imports: import numpy
  import pandas
  from mlxtend.preprocessing import standardize
label_desc: Use image node_id 1 for calling a global function with example usage: test_pandas_standardize() without return types