smape1

HydroErr.HydroErr.smape1(simulated_array, observed_array, replace_nan=None, replace_inf=None, remove_neg=False, remove_zero=False)

Compute the the Symmetric Mean Absolute Percentage Error (1) (SMAPE1).

../_images/SMAPE1.png

Range: 0 ≤ SMAPE1 < 100%, smaller is better, symmetrical.

Notes: This metric is an adjusted version of the MAPE.

Parameters:
  • simulated_array (one dimensional ndarray) – An array of simulated data from the time series.
  • observed_array (one dimensional ndarray) – An array of observed data from the time series.
  • replace_nan (float, optional) – If given, indicates which value to replace NaN values with in the two arrays. If None, when a NaN value is found at the i-th position in the observed OR simulated array, the i-th value of the observed and simulated array are removed before the computation.
  • replace_inf (float, optional) – If given, indicates which value to replace Inf values with in the two arrays. If None, when an inf value is found at the i-th position in the observed OR simulated array, the i-th value of the observed and simulated array are removed before the computation.
  • remove_neg (boolean, optional) – If True, when a negative value is found at the i-th position in the observed OR simulated array, the i-th value of the observed AND simulated array are removed before the computation.
  • remove_zero (boolean, optional) – If true, when a zero value is found at the i-th position in the observed OR simulated array, the i-th value of the observed AND simulated array are removed before the computation.
Returns:

The symmetric mean absolute percentage error (1).
Return type:

float

Examples

Note that if we switch the simulated and observed arrays the result is the same

>>> import HydroErr as he
>>> import numpy as np

>>> sim = np.array([5, 7, 9, 2, 4.5, 6.7])
>>> obs = np.array([4.7, 6, 10, 2.5, 4, 7])
>>> he.smape1(sim, obs)
5.871915694397428
>>> he.smape1(obs, sim)
5.871915694397428

References

  • Flores, B.E., 1986. A pragmatic view of accuracy measurement in forecasting. Omega 14(2) 93-98.
  • Goodwin, P., Lawton, R., 1999. On the asymmetry of the symmetric MAPE. International Journal of Forecasting 15(4) 405-408.