[5] Writer

cgsmiles/graph_utils.py

@@ -69,9 +69,9 @@ def sort_nodes_by_attr(graph, sort_attr="fragid"):
     nx.Graph
         graph with nodes sorted in correct order
     """
-    attr_values = nx.get_node_attributes(graph, sort_attr)
-    sorted_ids = sorted(attr_values, key=lambda item: (attr_values[item], item))
-    mapping = {old: new for new, old in enumerate(sorted_ids)}
+    fragids = nx.get_node_attributes(graph, sort_attr)
+    sorted_ids = sorted(fragids.items(), key=lambda item: (item[1], item[0]))
+    mapping = {old[0]: new for new, old in enumerate(sorted_ids)}
     new_graph = nx.relabel_nodes(graph, mapping, copy=True)
     return new_graph
 

cgsmiles/read_fragments.py

@@ -78,6 +78,8 @@ def strip_bonding_descriptors(fragment_string):
                 elif current_order:
                     order = current_order
                     current_order = None
+                    # we need to remove the symbol from the clean string
+                    smile = smile[:-1]
                 else:
                     order = 1
                 bonding_descrpt[prev_node].append(bond_descrp + str(order))
@@ -141,6 +143,7 @@ def fragment_iter(fragment_str, all_atom=True):
         fragname = fragment[1:delim]
         big_smile = fragment[delim+1:]
         smile, bonding_descrpt = strip_bonding_descriptors(big_smile)
+        print(smile)
         if smile == "H":
             mol_graph = nx.Graph()
             mol_graph.add_node(0, element="H", bonding=bonding_descrpt[0])

cgsmiles/tests/test_write_cgsmiles.py

@@ -0,0 +1,42 @@
+import pytest
+from pysmiles.testhelper import assertEqualGraphs
+from cgsmiles.read_fragments import read_fragments
+from cgsmiles.read_cgsmiles import read_cgsmiles
+from cgsmiles.write_cgsmiles import write_cgsmiles_fragments, write_cgsmiles_graph
+
+@pytest.mark.parametrize('input_string',(
+                        # smiple linear seqeunce
+                        "{#PEO=[$]COC[$],#OHter=[$]O}",
+                        # two bonding IDs
+                        "{#PEO=[$][$A]COC[$][$B],#OHter=[$]O}",
+                        # something with bond order
+                        "{#PEO=[$]=COC[$A],#OHter=[$A]O,#PI=[$]=C}",
+                        # something with a shash operator
+                        "{#TC5=[!]CCC[!],#TN6a=[!]CNC[!]}",
+                        # something with aromatic fragments
+                        "{#TC5=[!]ccc[!],#TN6a=[!]cnc[!]}",
+))
+def test_write_fragments(input_string):
+    frag_dict = read_fragments(input_string)
+    out_string = write_cgsmiles_fragments(frag_dict, all_atom=True)
+    frag_dict_out = read_fragments(out_string)
+    for fragname in frag_dict:
+        assertEqualGraphs(frag_dict_out[fragname], frag_dict[fragname])
+
+@pytest.mark.parametrize('input_string',(
+                        # smiple linear seqeunce
+                        "{[#PEO][#PMA]}",
+                        # ring
+                        "{[#TC5]1[#TC5][#TC5][#TC5][#TC5]1}",
+                        # branched
+                        "{[#PE][#PMA]([#PEO][#PEO][#PEO])[#PE]}",
+                        # branched nested
+                        "{[#PE][#PMA]([#PEO][#PEO]([#OMA][#OMA]1[#OMA][#OMA]1))[#PE]}",
+                        # special cycle
+                        "{[#PE]1[#PMA]1}",
+))
+def test_write_mol_graphs(input_string):
+    mol_graph = read_cgsmiles(input_string)
+    out_string = write_cgsmiles_graph(mol_graph)
+    out_graph = read_cgsmiles(out_string)
+    assertEqualGraphs(mol_graph, out_graph)

cgsmiles/write_cgsmiles.py

@@ -0,0 +1,240 @@
+from collections import defaultdict
+import networkx as nx
+from pysmiles.smiles_helper import format_atom
+from pysmiles.write_smiles import _get_ring_marker,_write_edge_symbol
+
+order_to_symbol = {0: '.', 1: '-', 1.5: ':', 2: '=', 3: '#', 4: '$'}
+
+def format_node(molecule, current):
+    """
+    Format a node from a `molecule` graph according to
+    the CGSmiles syntax. The attribute fragname has to
+    be set for the `current` node.
+
+    Parameters
+    ----------
+    molecule: nx.Graph
+    current: abc.hashbale
+
+    Returns
+    -------
+    str
+        the formatted string
+    """
+    node = "[#{}]".format(molecule.nodes[current]['fragname'])
+    return node
+
+def format_bonding(bonding):
+    """
+    Given the list of bonding descriptors format them
+    such that they can be added after a node/atom. This
+    function wraps the descriptor in [ ] braces and makes
+    sure that the bond order annotation is removed.
+
+    Parameters
+    ----------
+    bonding: list[str]
+        list of bonding descriptors
+
+    Returns
+    -------
+    str
+        the formatted bonding descriptor string
+    """
+    bond_str = ""
+    for bonding_descrpt in bonding:
+        bond_order = bonding_descrpt[-1]
+        order_symb = order_to_symbol[int(bond_order)]
+        if order_symb != '-':
+            bond_str = order_symb
+        bond_str += "["+str(bonding_descrpt[:-1])+"]"
+    return bond_str
+
+def write_graph(molecule, smiles_format=False, default_element='*'):
+    """
+    Creates a CGsmiles string describing `molecule`.
+    `molecule` should be a single connected component.
+
+    Parameters
+    ----------
+    molecule : nx.Graph
+        The molecule for which a CGsmiles string should be generated.
+    smiles_format:
+        If the nodes are written using the OpenSmiles standard format.
+
+    Returns
+    -------
+    str
+        The CGSmiles string describing `molecule`.
+    """
+    # should be any node with order 1
+    start = min(molecule)
+    dfs_successors = nx.dfs_successors(molecule, source=start)
+
+    predecessors = defaultdict(list)
+    for node_key, successors in dfs_successors.items():
+        for successor in successors:
+            predecessors[successor].append(node_key)
+    predecessors = dict(predecessors)
+    # We need to figure out which edges we won't cross when doing the dfs.
+    # These are the edges we'll need to add to the smiles using ring markers.
+    edges = set()
+    for n_idx, n_jdxs in dfs_successors.items():
+        for n_jdx in n_jdxs:
+            edges.add(frozenset((n_idx, n_jdx)))
+    total_edges = set(map(frozenset, molecule.edges))
+    ring_edges = total_edges - edges
+
+    # in cgsmiles bond orders represent rings
+    # beteween consecutive nodes so we need to
+    # add them to the ring list
+    if not smiles_format:
+        for edge in molecule.edges:
+            if molecule.edges[edge]['order'] == 2:
+                ring_edges.add(frozenset(edge))
+
+    atom_to_ring_idx = defaultdict(list)
+    ring_idx_to_bond = {}
+    ring_idx_to_marker = {}
+    for ring_idx, (n_idx, n_jdx) in enumerate(ring_edges, 1):
+        atom_to_ring_idx[n_idx].append(ring_idx)
+        atom_to_ring_idx[n_jdx].append(ring_idx)
+        ring_idx_to_bond[ring_idx] = (n_idx, n_jdx)
+
+    branch_depth = 0
+    branches = set()
+    to_visit = [start]
+    smiles = ''
+
+    while to_visit:
+        current = to_visit.pop()
+        if current in branches:
+            branch_depth += 1
+            smiles += '('
+            branches.remove(current)
+
+        if current in predecessors:
+            # It's not the first atom we're visiting, so we want to see if the
+            # edge we last crossed to get here is interesting.
+            previous = predecessors[current]
+            assert len(previous) == 1
+            previous = previous[0]
+            if smiles_format and _write_edge_symbol(molecule, previous, current):
+                order = molecule.edges[previous, current].get('order', 1)
+                smiles += order_to_symbol[order]
+
+        if smiles_format:
+            smiles += format_atom(molecule, current, default_element)
+        else:
+            smiles += format_node(molecule, current)
+
+        # we add the bonding descriptors if there are any
+        if molecule.nodes[current].get('bonding', False):
+            smiles += format_bonding(molecule.nodes[current]['bonding'])
+
+        if current in atom_to_ring_idx:
+            # We're going to need to write a ring number
+            ring_idxs = atom_to_ring_idx[current]
+            for ring_idx in ring_idxs:
+                ring_bond = ring_idx_to_bond[ring_idx]
+                if ring_idx not in ring_idx_to_marker:
+                    marker = _get_ring_marker(ring_idx_to_marker.values())
+                    ring_idx_to_marker[ring_idx] = marker
+                    new_marker = True
+                else:
+                    marker = ring_idx_to_marker.pop(ring_idx)
+                    new_marker = False
+
+                if smiles_format and _write_edge_symbol(molecule, *ring_bond) and new_marker:
+                    order = molecule.edges[ring_bond].get('order', 1)
+                    smiles += order_to_symbol[order]
+
+                smiles += str(marker) if marker < 10 else '%{}'.format(marker)
+
+        if current in dfs_successors:
+            # Proceed to the next node in this branch
+            next_nodes = dfs_successors[current]
+            # ... and if needed, remember to return here later
+            branches.update(next_nodes[1:])
+            to_visit.extend(next_nodes)
+        elif branch_depth:
+            # We're finished with this branch.
+            smiles += ')'
+            branch_depth -= 1
+
+    smiles += ')' * branch_depth
+    return smiles
+
+def write_cgsmiles_graph(molecule):
+    """
+    Write a CGSmiles graph sans fragments at
+    different resolution.
+
+    Parameters
+    ----------
+    molecule: nx.Graph
+        a molecule where each node as a fragname attribute
+        that is used as name in the CGSmiles string.
+
+    Returns
+    -------
+    str
+        the CGSmiles string
+    """
+
+    cgsmiles_str = write_graph(molecule)
+    return "{" + cgsmiles_str + "}"
+
+def write_cgsmiles_fragments(fragment_dict, all_atom=True):
+    """
+    Write fragments of molecule graph. To identify the fragments
+    all nodes with the same `fragname` and `fragid` attributes
+    are considered as fragment. Bonding between fragments is
+    extracted from the `bonding` edge attributes.
+
+    Parameters
+    ----------
+    fragment_dict: dict[str, nx.Graph]
+        a dict of fragment graphs
+    all_atom: bool
+        write all atom SMILES if True (default) otherwise
+        write CGSmiles
+
+    Returns
+    -------
+    str
+    """
+    fragment_str = ""
+    for fragname, frag_graph in fragment_dict.items():
+        fragment_str += f"#{fragname}="
+        # format graph depending on resolution
+        fragment_str += write_graph(frag_graph, smiles_format=all_atom) + ","
+    fragment_str = "{" + fragment_str[:-1] + "}"
+    return fragment_str
+
+def write_cgsmiles(molecule_graph, fragments, last_all_atom=True):
+    """
+    Write a CGSmiles string given a low resolution molecule graph
+    and any number of higher resolutions provided as fragment dicts.
+
+    Parameters
+    ----------
+    molecule_graph: nx.Graph
+    fragments: list[dict[nx.Graph]]
+        a list of fragment dicts
+    last_all_atom: bool
+        if the last set of fragments is at the all_atom level
+
+    Returns
+    -------
+    str
+        CGSmiles string
+    """
+    final_str = write_cgsmiles_graph(molecule)
+    for layer, fragment in enumerate(fragments):
+        if layer == len(fragments)-1 and last_all_atom:
+            fragment_str = write_cgsmiles_fragments(fragment, smiles_format=True)
+        else:
+            fragment_str = write_cgsmiles_fragments(fragment, smiles_format=False)
+        final_str += "." + fragment_str
+    return final_str