code: def test_df_to_array(self):
      df = pd.DataFrame([1, 2, 3], columns=["col"])
      expected = np.array([[1], [2], [3]])
      t = _df_to_array(df)
      assert np.array_equal(t, expected)
  
file_path: shapash/tests/unit_tests/utils/test_explanation_metrics.py
imports: import unittest
  import numpy
  import pandas
  from sklearn.linear_model import LinearRegression
  from shapash.utils.explanation_metrics import _df_to_array, _compute_distance, _compute_similarities, _get_radius, find_neighbors, shap_neighbors, get_min_nb_features, get_distance
label_desc: Use image node_id 1 for calling the TestExplanationMetrics obj's underlying member method code with example usage: obj.test_df_to_array() without return types