src.forcefield (28 February 2006) | index /Users/baker/coding/manifold/pdb2pqr/trunk/pdb2pqr/src/forcefield.py

`Forcefield.py
This module takes a pdblist as input and replaces the occupancy and
tempfactor fields with charge and radius fields, with values as defined
by a particular forcefield. The forcefield structure is modeled off of
the structures.py file, where each forcefield is considered a chain of
residues of atoms.
----------------------------
PDB2PQR -- An automated pipeline for the setup, execution, and analysis of
Poisson-Boltzmann electrostatics calculations
Nathan A. Baker (baker@biochem.wustl.edu)
Todd Dolinsky (todd@ccb.wustl.edu)
Dept. of Biochemistry and Molecular Biophysics
Center for Computational Biology
Washington University in St. Louis
Jens Nielsen (Jens.Nielsen@ucd.ie)
University College Dublin
Additional contributing authors listed in documentation and supporting
package licenses.
Copyright (c) 2003-2007. Washington University in St. Louis.
All Rights Reserved.
This file is part of PDB2PQR.
PDB2PQR is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
PDB2PQR is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with PDB2PQR; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
----------------------------`

Modules
`` |  |
getopt math | os re | xml.sax string | sys

Classes
`` |  | Forcefield ForcefieldAtom ForcefieldResidue xml.sax.handler.ContentHandler ForcefieldHandler
class Forcefield
`` | `Forcefield class The forcefield class contains definitions for a given forcefield. Each forcefield object contains a dictionary of residues, with each residue containing a dictionary of atoms. Dictionaries are used instead of lists as the ordering is not important. The forcefield definition files are unedited, directly from the forcefield - all transformations are done within.`
| Methods defined here: __init__(self, ff, definition, userff) `Initialize the class by parsing the definition file Parameters ff: The name of the forcefield (string) definition: The definition objects userff: A link to the file for CGI based user-defined forcefields` getGroup(self, resname, atomname) `Get the group/type associated with the input fields. If not found, return a null string. Parameters: resname: The residue name (string) atomname: The atom name (string)` getNames(self, resname, atomname) `Get the actual names associated with the input fields. The names passed in point to ForcefieldResidue and ForcefieldAtom objects which may have different names; grab these names and return. Parameters resname: The residue name (string) atomname: The atom name (string) Returns rname: The forcefield's name for this residue (string) aname: The forcefield's name for this atom (string)` getParams(self, resname, atomname) `Get the parameters associated with the input fields. The residue itself is needed instead of simply its name because the forcefield may use a different residue name than the standard amino acid name. Parameters resname: The residue name (string) atomname: The atom name (string) Returns charge: The charge on the atom (float) radius: The radius of the atom (float)` getResidue(self, resname) `Return the residue object with the given resname Parameters resname: The name of the residue (string) Returns residue: The residue object (ForcefieldResidue)` hasResidue(self, resname) `Check if the residue name is in the map or not. Parameters resname: The name to search for (string) Returns 1 if the resname is in the map, 0 otherwise.`
class ForcefieldAtom
`` | `ForcefieldAtom class The ForcefieldAtom object contains fields that are related to the forcefield at the atom level`
| Methods defined here: __init__(self, name, charge, radius, resname, group='') `Initialize the object Parameters name: The atom name (string) charge: The charge on the atom (float) radius: The radius of the atom (float) resname: The residue name (string) group: The group name (string)` __str__(self) `String representation of the forcefield atom.` get(self, name) `Get a member of the ForcefieldAtom class Parameters name: The name of the member (string) Possible Values name: The atom name (string) charge: The charge on the atom (float) radius: The radius of the atom (float) epsilon: The epsilon assocaited with the atom (float) Returns item: The value of the member`
class ForcefieldHandler(xml.sax.handler.ContentHandler)
`` |  | Methods defined here: __init__(self, map, reference) characters(self, text) `Store the information in the object for future use/ Parameters text: The text value between the XML tags` endElement(self, name) `At the end of the element, act on the stored information. Parameters name: The name of the element (string)` findMatchingNames(self, regname, map) `Find a list of strings that match the given regular expression. Parameters regname: The regular expression (string) map: The dictionary to search (dict) Returns list: A list of regular expression objects that match the regular expression.` startElement(self, name, attributes) `Override the startElement function to keep track of the current element.` updateMap(self, toname, fromname, map) `Update the given map by adding a pointer from a new name to an object. Parameters toname: The new name for the object (string) fromname: The old name for the object (string) map: A dictionary of items (dict)` Methods inherited from xml.sax.handler.ContentHandler: endDocument(self) `Receive notification of the end of a document. The SAX parser will invoke this method only once, and it will be the last method invoked during the parse. The parser shall not invoke this method until it has either abandoned parsing (because of an unrecoverable error) or reached the end of input.` endElementNS(self, name, qname) `Signals the end of an element in namespace mode. The name parameter contains the name of the element type, just as with the startElementNS event.` endPrefixMapping(self, prefix) `End the scope of a prefix-URI mapping. See startPrefixMapping for details. This event will always occur after the corresponding endElement event, but the order of endPrefixMapping events is not otherwise guaranteed.` ignorableWhitespace(self, whitespace) `Receive notification of ignorable whitespace in element content. Validating Parsers must use this method to report each chunk of ignorable whitespace (see the W3C XML 1.0 recommendation, section 2.10): non-validating parsers may also use this method if they are capable of parsing and using content models. SAX parsers may return all contiguous whitespace in a single chunk, or they may split it into several chunks; however, all of the characters in any single event must come from the same external entity, so that the Locator provides useful information.` processingInstruction(self, target, data) `Receive notification of a processing instruction. The Parser will invoke this method once for each processing instruction found: note that processing instructions may occur before or after the main document element. A SAX parser should never report an XML declaration (XML 1.0, section 2.8) or a text declaration (XML 1.0, section 4.3.1) using this method.` setDocumentLocator(self, locator) `Called by the parser to give the application a locator for locating the origin of document events. SAX parsers are strongly encouraged (though not absolutely required) to supply a locator: if it does so, it must supply the locator to the application by invoking this method before invoking any of the other methods in the DocumentHandler interface. The locator allows the application to determine the end position of any document-related event, even if the parser is not reporting an error. Typically, the application will use this information for reporting its own errors (such as character content that does not match an application's business rules). The information returned by the locator is probably not sufficient for use with a search engine. Note that the locator will return correct information only during the invocation of the events in this interface. The application should not attempt to use it at any other time.` skippedEntity(self, name) `Receive notification of a skipped entity. The Parser will invoke this method once for each entity skipped. Non-validating processors may skip entities if they have not seen the declarations (because, for example, the entity was declared in an external DTD subset). All processors may skip external entities, depending on the values of the http://xml.org/sax/features/external-general-entities and the http://xml.org/sax/features/external-parameter-entities properties.` startDocument(self) `Receive notification of the beginning of a document. The SAX parser will invoke this method only once, before any other methods in this interface or in DTDHandler (except for setDocumentLocator).` startElementNS(self, name, qname, attrs) `Signals the start of an element in namespace mode. The name parameter contains the name of the element type as a (uri, localname) tuple, the qname parameter the raw XML 1.0 name used in the source document, and the attrs parameter holds an instance of the Attributes class containing the attributes of the element. The uri part of the name tuple is None for elements which have no namespace.` startPrefixMapping(self, prefix, uri) `Begin the scope of a prefix-URI Namespace mapping. The information from this event is not necessary for normal Namespace processing: the SAX XML reader will automatically replace prefixes for element and attribute names when the http://xml.org/sax/features/namespaces feature is true (the default). There are cases, however, when applications need to use prefixes in character data or in attribute values, where they cannot safely be expanded automatically; the start/endPrefixMapping event supplies the information to the application to expand prefixes in those contexts itself, if necessary. Note that start/endPrefixMapping events are not guaranteed to be properly nested relative to each-other: all startPrefixMapping events will occur before the corresponding startElement event, and all endPrefixMapping events will occur after the corresponding endElement event, but their order is not guaranteed.`
class ForcefieldResidue
`` | `ForcefieldResidue class The ForceFieldResidue class contains a mapping of all atoms within the residue for easy searching.`
| Methods defined here: __init__(self, name) `Initialize the ForceFieldResidue object Parameters name: The name of the residue (string)` addAtom(self, atom) `Add an atom to the ForcefieldResidue Parameters atom: The atom to be added (atom)` getAtom(self, atomname) `Return the atom object with the given atomname Parameters resname: The name of the atom (string) Returns residue: The atom object (ForcefieldAtom)` getAtoms(self) `Return the list of atoms in this residue.` hasAtom(self, atomname) `Check to see if the atomname is in the current residue. Parameters atomname: The name of the atom to search for Returns 1 if the atom is present in the residue, 0 otherwise`

Data
`` |  | DIHEDRAL = 57.2958 SMALL = 9.9999999999999995e-08 __author__ = 'Todd Dolinsky' __date__ = '28 February 2006'

Author
`` |  | Todd Dolinsky