code: def test_repr_str():
      exog = pd.DataFrame([[0, 0]], columns=["a", "b"])
      spec = specification.SARIMAXSpecification(
          exog=exog, order=(1, 1, 1), seasonal_order=(1, 1, 1, 4)
      )
      p = params.SARIMAXParams(spec=spec)
  
      # Check when we haven't given any parameters
      assert_equal(
          repr(p),
          "SARIMAXParams(exog=[nan nan], ar=[nan], ma=[nan],"
          " seasonal_ar=[nan], seasonal_ma=[nan], sigma2=nan)",
      )
      # assert_equal(str(p), '[nan nan nan nan nan nan nan]')
  
      p.exog_params = [1, 2]
      assert_equal(
          repr(p),
          "SARIMAXParams(exog=[1. 2.], ar=[nan], ma=[nan],"
          " seasonal_ar=[nan], seasonal_ma=[nan], sigma2=nan)",
      )
      # assert_equal(str(p), '[ 1.  2. nan nan nan nan nan]')
  
      p.ar_params = [0.5]
      assert_equal(
          repr(p),
          "SARIMAXParams(exog=[1. 2.], ar=[0.5], ma=[nan],"
          " seasonal_ar=[nan], seasonal_ma=[nan], sigma2=nan)",
      )
      # assert_equal(str(p), '[1.  2.  0.5 nan nan nan nan]')
  
      p.ma_params = [0.2]
      assert_equal(
          repr(p),
          "SARIMAXParams(exog=[1. 2.], ar=[0.5], ma=[0.2],"
          " seasonal_ar=[nan], seasonal_ma=[nan], sigma2=nan)",
      )
      # assert_equal(str(p), '[1.  2.  0.5 0.2 nan nan nan]')
  
      p.seasonal_ar_params = [0.001]
      assert_equal(
          repr(p),
          "SARIMAXParams(exog=[1. 2.], ar=[0.5], ma=[0.2],"
          " seasonal_ar=[0.001], seasonal_ma=[nan],"
          " sigma2=nan)",
      )
      # assert_equal(str(p),
      #              '[1.e+00 2.e+00 5.e-01 2.e-01 1.e-03    nan    nan]')
  
      p.seasonal_ma_params = [-0.001]
      assert_equal(
          repr(p),
          "SARIMAXParams(exog=[1. 2.], ar=[0.5], ma=[0.2],"
          " seasonal_ar=[0.001], seasonal_ma=[-0.001],"
          " sigma2=nan)",
      )
      # assert_equal(str(p), '[ 1.e+00  2.e+00  5.e-01  2.e-01  1.e-03'
      #                      ' -1.e-03     nan]')
  
      p.sigma2 = 10.123
      assert_equal(
          repr(p),
          "SARIMAXParams(exog=[1. 2.], ar=[0.5], ma=[0.2],"
          " seasonal_ar=[0.001], seasonal_ma=[-0.001],"
          " sigma2=10.123)",
      )
  
file_path: statsmodels/statsmodels/tsa/arima/tests/test_params.py
imports: import numpy
  import pandas
  from numpy.testing import assert_, assert_equal, assert_allclose, assert_raises
  from statsmodels.tsa.arima import specification, params
label_desc: Use image node_id 11 for calling a global function with example usage: test_repr_str() without return types