MultipleSeqAlignment del method for removing sequences by index or sl…

…ice (biopython#4293)

* MultipleSeqAlignment del method added, closes issue 4137
* Changed the test to include the del method of MultipleSeqAlignment
* Added my name to the alphabetical listing

Bio/Align/__init__.py

@@ -791,6 +791,13 @@ def __getitem__(self, index):
                     new.column_annotations[k] = v[col_index]
             return new
 
+    def __delitem__(self, index):
+        """Delete SeqRecord by index or multiple SeqRecords by slice."""
+        if not isinstance(index, int) and not isinstance(index, slice):
+            raise TypeError("Invalid index type.")
+
+        del self._records[index]
+
     def sort(self, key=None, reverse=False):
         """Sort the rows (SeqRecord objects) of the alignment in place.
 

CONTRIB.rst

@@ -286,6 +286,7 @@ please open an issue on GitHub or mention it on the mailing list.
 - Shoichiro Kawauchi <https://github.com/lacrosse91>
 - Shuichiro MAKIGAKI <https://github.com/shuichiro-makigaki>
 - Shyam Saladi <https://github.com/smsaladi>
+- Siddharta Morion <https://github.com/siddhartasr10>
 - Siong Kong <https://github.com/siongkong>
 - Sjoerd de Vries <https://github.com/sjdv1982>
 - Soroush Saffari <https://github.com/sorsaffari>

Tests/test_align.py

@@ -176,6 +176,8 @@ def test_basic_alignment(self):
         alignment.append(SeqRecord(Seq(letters), id="mixed"))
         alignment.append(SeqRecord(Seq(letters.lower()), id="lower"))
         alignment.append(SeqRecord(Seq(letters.upper()), id="upper"))
+        alignment.append(SeqRecord(Seq(letters), id="duplicate"))
+        del alignment[3]
         self.assertEqual(alignment.get_alignment_length(), 26)
         self.assertEqual(len(alignment), 3)
         self.assertEqual(alignment[0].seq, letters)