Avoid using deprecated "feasible" property (#631)

The "feasible" property of pymoo.core.individual.Individual got
deprecated in commit ad3ef60 but was
still used internally, thus producing deprecation warnings in user code.
Use the FEAS property instead.

pymoo/core/algorithm.py

@@ -261,7 +261,7 @@ def result(self):
             opt = None
 
         # if no feasible solution has been found
-        elif not np.any(opt.get("feasible")):
+        elif not np.any(opt.get("FEAS")):
             if self.return_least_infeasible:
                 opt = filter_optimum(opt, least_infeasible=True)
             else:

pymoo/core/replacement.py

@@ -59,8 +59,8 @@ def _do(self, problem, pop, off, **kwargs):
 
         ret = np.full((len(pop), 1), False)
 
-        pop_F, pop_CV, pop_feas = pop.get("F", "CV", "feasible")
-        off_F, off_CV, off_feas = off.get("F", "CV", "feasible")
+        pop_F, pop_CV, pop_feas = pop.get("F", "CV", "FEAS")
+        off_F, off_CV, off_feas = off.get("F", "CV", "FEAS")
 
         if problem.has_constraints() > 0:
 

pymoo/core/survival.py

@@ -86,7 +86,7 @@ def _do(self, problem, pop, off, **kwargs):
 
 
 def split_by_feasibility(pop, sort_infeas_by_cv=True, sort_feas_by_obj=False, return_pop=False):
-    F, CV, b = pop.get("F", "CV", "feasible")
+    F, CV, b = pop.get("F", "CV", "FEAS")
 
     feasible = np.where(b)[0]
     infeasible = np.where(~b)[0]

pymoo/util/misc.py

@@ -360,7 +360,7 @@ def intersect(a, b):
 
 
 def has_feasible(pop):
-    return np.any(pop.get("feasible"))
+    return np.any(pop.get("FEAS"))
 
 
 def to_numpy(a):

pymoo/util/normalization.py

@@ -305,7 +305,7 @@ def __init__(self) -> None:
         self._worst = None
 
     def update(self, pop):
-        F, feas = pop.get("F", "feasible")
+        F, feas = pop.get("F", "FEAS")
         self._infeas_ideal = find_ideal(F, current=self._infeas_ideal)
 
         if np.any(feas):