new commit: retain reset_state() function capability with single call…

… in apparent_mb_from_any_mb subject to kwarg, no other changes

docs/whats-new.rst

@@ -21,15 +21,13 @@ Enhancements
   ``dis_from_border``, ...) to define this ranking, providing greater flexibility
   and control over how the melting sequence is visualized (:pull:`1746`).
   By `Patrick Schmitt <https://github.com/pat-schmitt>`_
-- Added "reset_state" functionality to ``MassBalanceModel.get_specific_mb()`` to 
-  signal any state-dependent mass balance model to "reset its state" at the start
-  of the period. This is achieved through a "reset_state" kwarg passed by 
-  ``MassBalanceModel.get_annual_mb()``. Done to address that 
-  ``apparent_mb_from_any_mb()`` calls ``get_specific_mb()``  twice, leading to nonzero
-  terminal flux (potentially) with a state-dependent mass balance model.
-  `apparent_mb_from_any_mb()` also changed accordingly. Similar change also 
-  made to ``MultipleFlowlineMassBalanceModel.get_specific_mb()``. Does not impact
-  any current functionality within oggm.
+- Added "reset_state()" function to ``MassBalanceModel`` to signal any state-dependent 
+  mass balance model to "reset its state" at the start of the period. This function
+  does nothing in the parent class and would only be implemented by a state-ful
+  mass balance model. Done mainly to address that ``apparent_mb_from_any_mb()`` calls 
+  ``get_specific_mb()``  twice, leading to nonzero terminal flux (potentially) with a 
+  state-dependent mass balance model. `apparent_mb_from_any_mb()` also changed 
+  accordingly. 
 
 Bug fixes
 ~~~~~~~~~

oggm/core/massbalance.py

@@ -68,7 +68,6 @@ def __repr__(self):
 
     def reset_state(self):
         """Reset any internal state of the model.
-
         This might not be needed by most models, but some models have an
         internal state (e.g. a snow cover history) which can be reset
         this way.
@@ -135,7 +134,7 @@ def get_annual_mb(self, heights, year=None, fl_id=None, fls=None):
         raise NotImplementedError()
 
     def get_specific_mb(self, heights=None, widths=None, fls=None,
-                        year=None, reset_state=False):
+                        year=None):
         """Specific mb for this year and a specific glacier geometry.
 
          Units: [mm w.e. yr-1], or millimeter water equivalent per year
@@ -153,27 +152,18 @@ def get_specific_mb(self, heights=None, widths=None, fls=None,
             provided.
         year: float, optional
             the time (in the "floating year" convention)
-        reset_state: bool, optional
-            if True, call mb_model.reset_state() before computing the
-            mass balance each year. This is useful for models that have
-            an internal state (in which case they need to implement the
-            reset_state() method).
+
         Returns
         -------
         the specific mass balance (units: mm w.e. yr-1)
         """
 
         if len(np.atleast_1d(year)) > 1:
             out = [self.get_specific_mb(heights=heights, widths=widths,
-                                        fls=fls, year=yr,
-                                        reset_state=reset_state) for yr in year]
+                                        fls=fls, year=yr)
+                   for yr in year]
             return np.asarray(out)
 
-        # The code above is a recursive call to the below, which is
-        # why we reset only now, if annual spec MB is needed.
-        if reset_state:
-            self.reset_state()
-
         if fls is not None:
             mbs = []
             widths = []
@@ -186,8 +176,7 @@ def get_specific_mb(self, heights=None, widths=None, fls=None,
                     pass
                 widths = np.append(widths, _widths)
                 mbs = np.append(mbs, self.get_annual_mb(fl.surface_h,
-                                                        fls=fls,
-                                                        fl_id=i,
+                                                        fls=fls, fl_id=i,
                                                         year=year))
         else:
             mbs = self.get_annual_mb(heights, year=year)
@@ -1315,7 +1304,7 @@ def get_annual_mb_on_flowlines(self, fls=None, year=None):
         return heights, widths, mbs
 
     def get_specific_mb(self, heights=None, widths=None, fls=None,
-                        year=None, reset_state=False):
+                        year=None):
 
         if heights is not None or widths is not None:
             raise ValueError('`heights` and `widths` kwargs do not work with '
@@ -1325,13 +1314,9 @@ def get_specific_mb(self, heights=None, widths=None, fls=None,
             fls = self.fls
 
         if len(np.atleast_1d(year)) > 1:
-            out = [self.get_specific_mb(fls=fls, year=yr, reset_state=reset_state)
-                   for yr in year]
+            out = [self.get_specific_mb(fls=fls, year=yr) for yr in year]
             return np.asarray(out)
 
-        if reset_state:
-            self.reset_state()
-
         mbs = []
         widths = []
         for i, (fl, mb_mod) in enumerate(zip(fls, self.flowline_mb_models)):
@@ -2110,8 +2095,7 @@ def to_minimize(ela_h):
 @entity_task(log, writes=['inversion_flowlines'])
 def apparent_mb_from_any_mb(gdir, mb_model=None,
                             mb_model_class=MonthlyTIModel,
-                            mb_years=None,
-                            reset_state=False):
+                            mb_years=None, reset_state=False):
     """Compute apparent mb from an arbitrary mass balance profile.
 
     This searches for a mass balance residual to add to the mass balance
@@ -2162,14 +2146,16 @@ def apparent_mb_from_any_mb(gdir, mb_model=None,
         mb_years = np.arange(*mb_years, 1)
 
     # Unchanged SMB
-    o_smb = np.mean(mb_model.get_specific_mb(fls=fls, year=mb_years,
-                                             reset_state=reset_state))
+    o_smb = np.mean(mb_model.get_specific_mb(fls=fls, year=mb_years))
 
     def to_minimize(residual_to_opt):
         return o_smb + residual_to_opt - cmb
 
     residual = optimize.brentq(to_minimize, -1e5, 1e5)
 
+    if (reset_state):
+        mb_model.reset_state()
+
     # Reset flux
     for fl in fls:
         fl.reset_flux()
@@ -2179,15 +2165,8 @@ def to_minimize(residual_to_opt):
     for fl_id, fl in enumerate(fls):
         mbz = 0
         for yr in mb_years:
-            if reset_state:
-                mb_model.reset_state()
-            if yr == mb_years[0]:
-                mbz += mb_model.get_annual_mb(fl.surface_h, year=yr,
-                                              fls=fls, fl_id=fl_id)
-            else:
-                mbz += mb_model.get_annual_mb(fl.surface_h, year=yr,
-                                              fls=fls, fl_id=fl_id)
-
+            mbz += mb_model.get_annual_mb(fl.surface_h, year=yr,
+                                          fls=fls, fl_id=fl_id)
         mbz = mbz / len(mb_years)
         fl.set_apparent_mb(mbz * cfg.SEC_IN_YEAR * rho + residual,
                            is_calving=is_calving)