Merge 8d9cb1b into 0f6bb59

deeprank/models/pair.py

@@ -0,0 +1,26 @@
+
+
+class Pair:
+    """ A hashable, comparable object for any set of two inputs where order doesn't matter.
+
+        Args:
+            item1 (object): the pair's first object
+            item2 (object): the pair's second object
+    """
+
+    def __init__(self, item1, item2):
+        self.item1 = item1
+        self.item2 = item2
+
+    def __hash__(self):
+        # The hash should be solely based on the two paired items, not on their order.
+        # So rearrange the two items and turn them into a hashable tuple.
+        return hash(tuple(sorted([self.item1, self.item2])))
+
+    def __eq__(self, other):
+        # Compare the pairs as sets, so the order doesn't matter.
+        return {self.item1, self.item2} == {other.item1, other.item2}
+
+    def __iter__(self):
+        # Iterate over the two items in the pair.
+        return iter([self.item1, self.item2])

deeprank/operate/pdb.py

@@ -0,0 +1,76 @@
+import numpy
+import logging
+
+from deeprank.models.pair import Pair
+
+
+_log = logging.getLogger(__name__)
+
+def get_squared_distance(position1, position2):
+    """Get squared euclidean distance, this is computationally cheaper that the euclidean distance
+
+        Args:
+            position1 (numpy vector): first position
+            position2 (numpy vector): second position
+
+        Returns (float): the squared distance
+    """
+
+    return numpy.sum(numpy.square(position1 - position2))
+
+
+def get_distance(position1, position2):
+    """ Get euclidean distance between two positions in space.
+
+        Args:
+            position1 (numpy vector): first position
+            position2 (numpy vector): second position
+
+        Returns (float): the distance
+    """
+
+    return numpy.sqrt(get_squared_distance(position1, position2))
+
+
+def get_residue_contact_atom_pairs(pdb2sql, chain_id, residue_number, max_interatomic_distance):
+    """ Find interatomic contacts around a residue.
+
+        Args:
+            pdb2sql (pdb2sql object): the pdb structure that we're investigating
+            chain_id (str): the chain identifier, where the residue is located
+            residue_number (int): the residue number of interest within the chain
+            max_interatomic_distance (float): maximum distance between two atoms
+
+        Returns ([Pair(int, int)]): pairs of atom numbers that contact each other
+    """
+
+    # Square the max distance, so that we can compare it to the squared euclidean distance between each atom pair.
+    squared_max_interatomic_distance = numpy.square(max_interatomic_distance)
+
+    # List all the atoms in the selected residue, take the coordinates while we're at it:
+    residue_atoms = pdb2sql.get('rowID,x,y,z', chainID=chain_id, resSeq=residue_number)
+    if len(residue_atoms) == 0:
+        raise ValueError("No residue found in chain {} with number {}".format(chain_id, residue_number))
+
+    # List all the atoms in the pdb file, take the coordinates while we're at it:
+    atoms = pdb2sql.get('rowID,x,y,z')
+
+    # Iterate over all the atoms in the pdb, to find neighbours.
+    contact_atom_pairs = set([])
+    for atom_nr, x, y, z in atoms:
+
+        atom_position = numpy.array([x, y, z])
+
+        # Within the atom iteration, iterate over the atoms in the residue:
+        for residue_atom_nr, residue_x, residue_y, residue_z in residue_atoms:
+
+            residue_position = numpy.array([residue_x, residue_y, residue_z])
+
+            # Check that the two atom numbers are not the same and check their distance:
+            if atom_nr != residue_atom_nr and \
+                    get_squared_distance(atom_position, residue_position) < squared_max_interatomic_distance:
+
+                contact_atom_pairs.add(Pair(residue_atom_nr, atom_nr))
+
+
+    return contact_atom_pairs

test/models/test_pair.py

@@ -0,0 +1,15 @@
+from nose.tools import eq_
+
+from deeprank.models.pair import Pair
+
+
+def test_order_independency():
+    # test comparing:
+    pair1 = Pair(1, 2)
+    pair2 = Pair(2, 1)
+    eq_(pair1, pair2)
+
+    # test hashing:
+    d = {pair1: 1}
+    d[pair2] = 2
+    eq_(d[pair1], 2)

test/operate/test_pdb.py

@@ -0,0 +1,45 @@
+import numpy
+import logging
+import pkg_resources
+import os
+
+from pdb2sql import pdb2sql
+from nose.tools import ok_
+
+from deeprank.operate.pdb import get_residue_contact_atom_pairs
+
+
+_log = logging.getLogger(__name__)
+
+def test_residue_contact_atoms():
+
+    pdb_path = os.path.join(pkg_resources.resource_filename(__name__, ''),
+                            "../1AK4/native/1AK4.pdb")
+
+    try:
+        pdb = pdb2sql(pdb_path)
+
+        contact_atom_pairs = get_residue_contact_atom_pairs(pdb, 'C', 145, 8.5)
+
+        # List all the atoms in the pairs that we found:
+        contact_atoms = set([])
+        for atom1, atom2 in contact_atom_pairs:
+            contact_atoms.add(atom1)
+            contact_atoms.add(atom2)
+
+        # Ask pdb2sql for the residue identifiers & atom names:
+        contact_atom_names = [tuple(x) for x in pdb.get("chainID,resSeq,name", rowID=list(contact_atoms))]
+    finally:
+        pdb._close()
+
+    # Now, we need to verify that the function "get_residue_contact_atom_pairs" returned the right pairs.
+    # We do so by selecting one close residue and one distant residue.
+
+    neighbour = ('C', 144, 'CA')  # this residue sits right next to the selected residue
+    distant = ('B', 134, 'OE2')  # this residue is very far away
+
+    # Check that the close residue is present in the list and that the distant residue is absent.
+
+    ok_(neighbour in contact_atom_names)
+
+    ok_(distant not in contact_atom_names)