def parse_stockholm()

in src/analysis/parsers.py [0:0]

• 33 lines of code
• 14 McCabe index (conditional complexity)

def parse_stockholm(stockholm_string: str) -> Msa:
  """Parses sequences and deletion matrix from stockholm format alignment.

  Args:
    stockholm_string: The string contents of a stockholm file. The first
      sequence in the file should be the query sequence.

  Returns:
    A tuple of:
      * A list of sequences that have been aligned to the query. These
        might contain duplicates.
      * The deletion matrix for the alignment as a list of lists. The element
        at `deletion_matrix[i][j]` is the number of residues deleted from
        the aligned sequence i at residue position j.
      * The names of the targets matched, including the jackhmmer subsequence
        suffix.
  """
  name_to_sequence = collections.OrderedDict()
  for line in stockholm_string.splitlines():
    line = line.strip()
    if not line or line.startswith(('#', '//')):
      continue
    name, sequence = line.split()
    if name not in name_to_sequence:
      name_to_sequence[name] = ''
    name_to_sequence[name] += sequence

  msa = []
  deletion_matrix = []

  query = ''
  keep_columns = []
  for seq_index, sequence in enumerate(name_to_sequence.values()):
    if seq_index == 0:
      # Gather the columns with gaps from the query
      query = sequence
      keep_columns = [i for i, res in enumerate(query) if res != '-']

    # Remove the columns with gaps in the query from all sequences.
    aligned_sequence = ''.join([sequence[c] for c in keep_columns])

    msa.append(aligned_sequence)

    # Count the number of deletions w.r.t. query.
    deletion_vec = []
    deletion_count = 0
    for seq_res, query_res in zip(sequence, query):
      if seq_res != '-' or query_res != '-':
        if query_res == '-':
          deletion_count += 1
        else:
          deletion_vec.append(deletion_count)
          deletion_count = 0
    deletion_matrix.append(deletion_vec)

  return Msa(sequences=msa,
             deletion_matrix=deletion_matrix,
             descriptions=list(name_to_sequence.keys()))