Correct behavior of L-curve selection methods

deerlab/selregparam.py

@@ -151,22 +151,22 @@ def register_ouputs(optout):
 
         # L-curve minimum-radius method (LR)
         if method == 'lr':
-            Eta = np.log(penalties)
-            Rho = np.log(residuals)
+            Eta = np.log(np.asarray(penalties)+1e-20)
+            Rho = np.log(np.asarray(residuals)+1e-20)
             dd = lambda x: (x-np.min(x))/(np.max(x)-np.min(x))
             functional = dd(Rho)**2 + dd(Eta)**2         
-
+            
         # L-curve maximum-curvature method (LC)
         elif method == 'lc': 
-            d1Residual = np.gradient(np.log(residuals))
+            d1Residual = np.gradient(np.log(np.asarray(residuals)+1e-20))
             d2Residual = np.gradient(d1Residual)
-            d1Penalty = np.gradient(np.log(penalties))
+            d1Penalty = np.gradient(np.log(np.asarray(penalties)+1e-20))
             d2Penalty = np.gradient(d1Penalty)
             functional = (d1Residual*d2Penalty - d2Residual*d1Penalty)/(d1Residual**2 + d1Penalty**2)**(3/2)
+            functional = -functional # Maximize instead of minimize 
 
         # Find minimum of the selection functional              
         alphaOpt = alphaCandidates[np.argmin(functional)]
-
     else: 
         raise KeyError("Search method not found. Must be either 'brent' or 'grid'.")
 

test/test_selregparam.py

@@ -175,7 +175,7 @@ def test_lc_value():
     "Check that the value returned by the LC selection method is correct"
 
     loga = get_alpha_from_method('lc')
-    logaref = -7.900  # Computed with DeerLab-Matlab (0.9.2)
+    logaref = -1.39
 
     assert abs(1-loga/logaref) < 0.20
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