lowered abundancy for dsk, exit when starting sequence not found in kmers

reads_consensus.py

@@ -51,7 +51,7 @@ def count_kmers_dsk(input_path: str, start_sequence: str) -> (str, dict):
     dsk_script_path = currentdir+"/dsk/build/bin/dsk"
     dsk_tempfile_path = currentdir+"/dsk/tmp/kmer_count"
     
-    min_occ = 2 # threshold of occurrences to save the kmer
+    min_occ = 1 # threshold of occurrences to save the kmer
 
     kmer_count_command = dsk_script_path+' -file '+input_path+' -out '+dsk_tempfile_path+' -kmer-size '+ str(KMER_SIZE)+' -abundance-min '+str(min_occ)+' -verbose 0'
     subprocess.call('/bin/bash -c "$DSK"', shell=True, env={'DSK': kmer_count_command})
@@ -77,10 +77,9 @@ def count_kmers_dsk(input_path: str, start_sequence: str) -> (str, dict):
     potential_starters_dict = dict((k,v) for k,v in kmer_occurrences_dict.items() if k.startswith(start_sequence))
     
     if len(potential_starters_dict) == 0:
-        print("kmer_consensus warning : starting sequence not found in the reads")
-        return
+        print("kmer_consensus error : starting sequence not found in the reads")
+        exit(1)
     start_kmer = max(potential_starters_dict, key=potential_starters_dict.get) # kmer with the maximum occurrences that begins with the starting sequence 
-
     return start_kmer, kmer_occurrences_dict