add "sequence" kwarg to Uniprot.seqScanning()

rhapsody/features/Uniprot.py

@@ -865,26 +865,44 @@ def mapSAVs2PDB(SAV_coords, custom_PDB=None, refresh=False,
     return mapped_SAVs
 
 
-def seqScanning(Uniprot_coord):
-    '''Returns a list of SAVs. If the string 'Uniprot_coord' is just a Uniprot ID,
-    the list will contain all possible amino acid substitutions at all positions
-    in the sequence. If 'Uniprot_coord' also includes a specific position, the list
-    will only contain all possible amino acid variants at that position.
+def seqScanning(Uniprot_coord, sequence=None):
+    '''Returns a list of SAVs. If the string 'Uniprot_coord' is just a
+    Uniprot ID, the list will contain all possible amino acid substitutions
+    at all positions in the sequence. If 'Uniprot_coord' also includes a
+    specific position, the list will only contain all possible amino acid
+    variants at that position. If 'sequence' is 'None' (default), the
+    sequence will be downloaded from Uniprot.
     '''
     assert isinstance(Uniprot_coord, str), "Must be a string."
     coord = Uniprot_coord.strip().split()
     assert len(coord) < 3, "Invalid format. Examples: 'Q9BW27' or 'Q9BW27 10'."
-    Uniprot_record = pd.queryUniprot(coord[0])
-    sequence = Uniprot_record['sequence   0'].replace("\n", "")
+    aa_list = 'ACDEFGHIKLMNPQRSTVWY'
+    if sequence is None:
+        Uniprot_record = pd.queryUniprot(coord[0])
+        sequence = Uniprot_record['sequence   0'].replace("\n", "")
+    else:
+        assert isinstance(sequence, str), "Must be a string."
+        sequence = sequence.upper()
+        assert set(sequence).issubset(aa_list), "Invalid list of amino acids."
     if len(coord) == 1:
+        # user asks for full-sequence scanning
         positions = range(len(sequence))
     else:
-        positions = [int(coord[1]) - 1]
+        # user asks for single-site scanning
+        site = int(coord[1])
+        positions = [site - 1]
+        # if user provides only one amino acid as 'sequence', interpret it
+        # as the amino acid at the specified position
+        if len(sequence) == 1:
+            sequence = sequence*site
+        else:
+            assert len(sequence) >= site, ("Requested position is not found "
+                                           "in input sequence.")
     SAV_list = []
     acc = coord[0]
     for i in positions:
         wt_aa = sequence[i]
-        for aa in 'ACDEFGHIKLMNPQRSTVWY':
+        for aa in aa_list:
             if aa == wt_aa:
                 continue
             s = ' '.join([acc, str(i+1), wt_aa, aa])