diff --git a/src/rail/estimation/algos/somoclu_som.py b/src/rail/estimation/algos/somoclu_som.py
index f4ccfc0..ec04f08 100644
--- a/src/rail/estimation/algos/somoclu_som.py
+++ b/src/rail/estimation/algos/somoclu_som.py
@@ -193,6 +193,10 @@ class SOMocluInformer(CatInformer):
                           gridtype=Param(str, 'rectangular', msg="Optional parameter to specify the grid form of the nodes:"
                                          + "* 'rectangular': rectangular neurons (default)"
                                          + "* 'hexagonal': hexagonal neurons"),
+                          n_epochs=Param(int, 10, msg="number of training epochs."),
+                          initialization=Param(str, 'pca', msg="method of initializing the SOM:"
+                                               +"* 'pca': principal componant analysis (default)"
+                                               +"* 'random' randomly initialize the SOM"),
                           maptype=Param(str, 'planar', msg="Optional parameter to specify the map topology:"
                                         + "* 'planar': Planar map (default)"
                                         + "* 'toroid': Toroid map"),
@@ -220,7 +224,7 @@ def run(self):
             if np.isnan(self.config.nondetect_val):  # pragma: no cover
                 mask = np.isnan(training_data[col])
             else:
-                mask = np.isclose(training_data[col], self.config.nondetect_val)
+                mask = np.logical_or(np.isinf(training_data[col]), np.isclose(training_data[col], self.config.nondetect_val))
             training_data[col][mask] = self.config.mag_limits[col]
 
         colors = _computemagcolordata(training_data, self.config.ref_band,
@@ -228,9 +232,9 @@ def run(self):
 
         som = Somoclu(self.config.n_columns, self.config.n_rows,
                       gridtype=self.config.gridtype, compactsupport=False,
-                      maptype=self.config.maptype, initialization='pca')
+                      maptype=self.config.maptype, initialization=self.config.initialization)
 
-        som.train(colors)
+        som.train(colors, epochs=self.config.n_epochs,)
 
         modeldict = dict(som=som, usecols=self.config.bands,
                          ref_column=self.config.ref_band,
@@ -323,7 +327,9 @@ class SOMocluSummarizer(SZPZSummarizer):
                           phot_weightcol=Param(str, "", msg="name of photometry weight, if present"),
                           spec_weightcol=Param(str, "", msg="name of specz weight col, if present"),
                           split=Param(int, 200, msg="the size of data chunks when calculating the distances between the codebook and data"),
-                          nsamples=Param(int, 20, msg="number of bootstrap samples to generate"))
+                          nsamples=Param(int, 20, msg="number of bootstrap samples to generate"),
+                          useful_clusters=Param(np.ndarray, np.array([]), msg="the cluster indices that are used for calibration. If not given, then "
+                                               +"all the clusters containing spec sample are used."),)
     outputs = [('output', QPHandle),
                ('single_NZ', QPHandle),
                ('cellid_output', Hdf5Handle),
@@ -400,7 +406,6 @@ def run(self):
 
         self.zgrid = np.linspace(self.config.zmin, self.config.zmax, self.config.nzbins + 1)
 
-
         if self.config.n_clusters > self.n_rows * self.n_columns:  # pragma: no cover
             print("Warning: number of clusters cannot be greater than the number of cells ("+str(self.n_rows * self.n_columns)+"). The SOM will NOT be grouped into clusters.")
             n_clusters = self.n_rows * self.n_columns
@@ -445,7 +450,7 @@ def run(self):
         N_eff_num = 0.
         N_eff_den = 0.
         phot_cluster_set = set()
-
+        bad_clusters = set()
         # make dictionary of ID data to be written out with cell IDs
         id_dict = {}
 
@@ -455,7 +460,7 @@ def run(self):
             print(f"Process {self.rank} running summarizer on chunk {s} - {e}")
 
             chunk_number = s//self.config.chunk_size
-            tmp_neff_num, tmp_neff_den = self._process_chunk(test_data, bootstrap_matrix, som_cluster_inds, spec_cluster_set, phot_cluster_set, sz, spec_data['weight'], spec_som_clusterind, N_eff_p_num, N_eff_p_den, hist_vals, id_dict, s, e, first)
+            tmp_neff_num, tmp_neff_den = self._process_chunk(test_data, bootstrap_matrix, som_cluster_inds, spec_cluster_set, phot_cluster_set, sz, spec_data['weight'], spec_som_clusterind, N_eff_p_num, N_eff_p_den, hist_vals, id_dict, s, e, first, bad_clusters)
             N_eff_num += tmp_neff_num
             N_eff_den += tmp_neff_den
             first = False
@@ -474,7 +479,8 @@ def run(self):
             hist_vals = self.comm.reduce(hist_vals)
             N_eff_num = self.comm.reduce(N_eff_num)
             N_eff_den = self.comm.reduce(N_eff_den)
-
+            bad_clusters = self.comm.reduce(bad_clusters)
+            
             phot_cluster_list=np.array(list(phot_cluster_set),dtype=int)
             phot_cluster_total=self.comm.gather(phot_cluster_list)
             
@@ -483,12 +489,8 @@ def run(self):
                 return
             phot_cluster_total=np.concatenate(phot_cluster_total)
             phot_cluster_set = set(phot_cluster_total)
-        uncovered_clusters = phot_cluster_set - spec_cluster_set
-        bad_cluster = dict(uncovered_clusters=np.array(list(uncovered_clusters)))
-        print("the following clusters contain photometric data but not spectroscopic data:")
-        print(uncovered_clusters)
-        useful_clusters = phot_cluster_set - uncovered_clusters
-        print(f"{len(useful_clusters)} out of {n_clusters} have usable data")
+                    
+        print(f"{len(self.useful_clusters)} out of {n_clusters} have usable data")
 
         # effective number defined in Heymans et al. (2012) to quantify the photometric representation.
         # also see Eq.7 in Wright et al. (2020).
@@ -507,9 +509,9 @@ def run(self):
         qp_d = qp.Ensemble(qp.hist, data=dict(bins=self.zgrid, pdfs=fid_hist))
         self.add_data('output', sample_ens)
         self.add_data('single_NZ', qp_d)
-        self.add_data('uncovered_cluster_file', bad_cluster)
+        self.add_data('uncovered_cluster_file', bad_clusters)
 
-    def _process_chunk(self, test_data, bootstrap_matrix, som_cluster_inds, spec_cluster_set, phot_cluster_set, sz, sweight, spec_som_clusterind, N_eff_p_num, N_eff_p_den, hist_vals, id_dict, start, end, first):
+    def _process_chunk(self, test_data, bootstrap_matrix, som_cluster_inds, spec_cluster_set, phot_cluster_set, sz, sweight, spec_som_clusterind, N_eff_p_num, N_eff_p_den, hist_vals, id_dict, start, end, first, bad_clusters):
 
         for col in self.usecols:
             if col not in test_data.keys():  # pragma: no cover
@@ -534,13 +536,30 @@ def _process_chunk(self, test_data, bootstrap_matrix, som_cluster_inds, spec_clu
         self._do_chunk_output(id_dict, start, end, first)
 
         chunk_phot_cluster_set = set(phot_som_clusterind)
-        useful_clusters = chunk_phot_cluster_set.intersection(spec_cluster_set)
         phot_cluster_set.update(chunk_phot_cluster_set)
-
+        uncovered_clusters = phot_cluster_set - spec_cluster_set
+        bad_cluster = dict(uncovered_clusters=np.array(list(uncovered_clusters)))
+        print("the following clusters contain photometric data but not spectroscopic data:")
+        print(uncovered_clusters)
+        
+        covered_clusters = phot_cluster_set - uncovered_clusters
+        if self.config.useful_clusters.size == 0:
+            self.useful_clusters = covered_clusters
+        else:  # pragma: no cover        
+            if set(self.config.useful_clusters) <= covered_clusters:
+                self.useful_clusters = self.config.useful_clusters
+            else:
+                print("Warning: input useful clusters is not a subset of spec-covered clusters."
+                     +"Taking the intersection.")                
+                self.useful_clusters = np.intersect1d(self.config.useful_clusters, np.asarray(list(covered_clusters)))
+                if self.useful_clusters.size == 0:  # pragma: no cover
+                    raise ValueError("Input useful clusters have no intersection with spec-covered clusters!")
+        
+        useful_clusters = self.useful_clusters
+        
         tmp_neff_num = np.sum(test_data['weight'])
         tmp_neff_den = np.sum(test_data['weight'] ** 2)
 
-
         for i in range(self.config.nsamples):
             bootstrap_indices = bootstrap_matrix[:,i]
             bs_specz = sz[bootstrap_indices]
diff --git a/tests/som/test_somoclu_summarizers.py b/tests/som/test_somoclu_summarizers.py
index 49cf4ba..7fa0954 100644
--- a/tests/som/test_somoclu_summarizers.py
+++ b/tests/som/test_somoclu_summarizers.py
@@ -54,16 +54,20 @@ def one_algo(key, inform_class, summarizer_class, summary_kwargs):
     fid_ens = qp.read(summarizer2.get_output(summarizer2.get_aliased_tag("single_NZ"), final_name=True))
     meanz = fid_ens.mean().flatten()
     assert np.isclose(meanz[0], 0.14414913252122552, atol=0.025)
+    
+    full_useful_clusters = np.asarray(list(summarizer2.useful_clusters))
+    full_uncovered_clusters = np.asarray(list(np.setdiff1d(np.arange(31*31), full_useful_clusters)))
+        
     os.remove(summarizer2.get_output(summarizer2.get_aliased_tag("output"), final_name=True))
     os.remove(f"tmpsomoclu_" + key + ".pkl")
-    return summary_ens
+    return summary_ens, full_useful_clusters, full_uncovered_clusters
 
 
 def test_SomocluSOM():
     summary_config_dict = {"n_rows": 21, "n_columns": 21, "column_usage": "colors"}
     inform_class = somoclu_som.SOMocluInformer
     summarizerclass = somoclu_som.SOMocluSummarizer
-    _ = one_algo("SOMomoclu", inform_class, summarizerclass, summary_config_dict)
+    _,_,_ = one_algo("SOMomoclu", inform_class, summarizerclass, summary_config_dict)
 
 
 def test_SomocluSOM_with_mag_and_colors():
@@ -98,19 +102,35 @@ def test_SomocluSOM_with_columns():
     }
     inform_class = somoclu_som.SOMocluInformer
     summarizerclass = somoclu_som.SOMocluSummarizer
+    _,_,_ = one_algo("SOMoclu_wmag", inform_class, summarizerclass, summary_config_dict)
+    
 
-    _ = one_algo("SOMoclu_wmag", inform_class, summarizerclass, summary_config_dict)
+def test_SomocluSOM_useful_clusters():
+    summary_config_dict = {"n_rows": 21, "n_columns": 21, "column_usage": "colors", "seed":0}
+    inform_class = somoclu_som.SOMocluInformer
+    summarizerclass = somoclu_som.SOMocluSummarizer
+    _, full_useful_clusters, full_uncovered_clusters = one_algo("SOMomoclu1", inform_class, summarizerclass, summary_config_dict)
+    
+    summary_config_dict = {"n_rows": 31, "n_columns": 31, "column_usage": "colors", "seed":0, "useful_clusters": np.arange(31*31)}
+    inform_class = somoclu_som.SOMocluInformer
+    summarizerclass = somoclu_som.SOMocluSummarizer
+    _ = one_algo("SOMomoclu2", inform_class, summarizerclass, summary_config_dict)  
+    
+    summary_config_dict = {"n_rows": 31, "n_columns": 31, "column_usage": "colors", "seed":0, "useful_clusters": full_uncovered_clusters}
+    inform_class = somoclu_som.SOMocluInformer
+    summarizerclass = somoclu_som.SOMocluSummarizer
+    _ = one_algo("SOMomoclu4", inform_class, summarizerclass, summary_config_dict) 
 
-def test_SomocluSOM_with_badinput():
+def test_SomocluSOM_wrong_column():
     summary_config_dict = {
         "n_rows": 21,
         "n_columns": 21,
-        "column_usage": "something",
+        "column_usage": "wrong_column",
         "objid_name": "id",
     }
     inform_class = somoclu_som.SOMocluInformer
     summarizerclass = somoclu_som.SOMocluSummarizer
     try:
-        one_algo("SOMoclu_wrong", inform_class, summarizerclass, summary_config_dict)
+        _ = one_algo("SOMoclu_wrongcolumn", inform_class, summarizerclass, summary_config_dict)
     except:
         return