5.1. Single Low-energy 3D Structures

  1import sys
  2import argparse
  3
  4import CDPL.Chem as Chem
  5import CDPL.ConfGen as ConfGen
  6
  7
  8# generates a low-energy 3D structure of the argument molecule using
  9# the provided initialized ConfGen.StructureGenerator instance
 10def gen3DStructure(mol: Chem.Molecule, struct_gen: ConfGen.StructureGenerator) -> int:
 11    # prepare the molecule for 3D structure generation
 12    ConfGen.prepareForConformerGeneration(mol) 
 13
 14    # generate the 3D structure
 15    status = struct_gen.generate(mol)             
 16    
 17    # if successful, store the generated conformer ensemble as
 18    # per atom 3D coordinates arrays (= the way conformers are represented in CDPKit)
 19    if status == ConfGen.ReturnCode.SUCCESS:
 20        struct_gen.setCoordinates(mol)                
 21        
 22    # return status code
 23    return status
 24        
 25def parseArgs() -> argparse.Namespace:
 26    parser = argparse.ArgumentParser(description='Generates conformer ensembles for the given input molecules.')
 27
 28    parser.add_argument('-i',
 29                        dest='in_file',
 30                        required=True,
 31                        metavar='<file>',
 32                        help='Molecule input file')
 33    parser.add_argument('-o',
 34                        dest='out_file',
 35                        required=True,
 36                        metavar='<file>',
 37                        help='Conformer ensemble output file')
 38    parser.add_argument('-t',
 39                        dest='max_time',
 40                        required=False,
 41                        metavar='<int>',
 42                        type=int,
 43                        default=3600,
 44                        help='Max. allowed molecule processing time (default: 3600 sec)')
 45    parser.add_argument('-q',
 46                        dest='quiet',
 47                        required=False,
 48                        action='store_true',
 49                        default=False,
 50                        help='Disable progress output (default: false)')
 51    
 52    return parser.parse_args()
 53
 54def main() -> None:
 55    args = parseArgs()
 56    
 57    # create reader for input molecules (format specified by file extension)
 58    reader = Chem.MoleculeReader(args.in_file) 
 59
 60    # create writer for the generated 3D structures (format specified by file extension)
 61    writer = Chem.MolecularGraphWriter(args.out_file) 
 62
 63    # export only a single 3D structure (in case of multi-conf. input molecules)
 64    Chem.setMultiConfExportParameter(writer, False)
 65    
 66    # create and initialize an instance of the class ConfGen.StructureGenerator which will
 67    # perform the actual 3D structure generation work
 68    struct_gen = ConfGen.StructureGenerator()
 69
 70    struct_gen.settings.timeout = args.max_time * 1000 # apply the -t argument
 71
 72    # dictionary mapping status codes to human readable strings
 73    status_to_str = { ConfGen.ReturnCode.UNINITIALIZED                  : 'uninitialized',
 74                      ConfGen.ReturnCode.TIMEOUT                        : 'max. processing time exceeded',
 75                      ConfGen.ReturnCode.ABORTED                        : 'aborted',
 76                      ConfGen.ReturnCode.FORCEFIELD_SETUP_FAILED        : 'force field setup failed',
 77                      ConfGen.ReturnCode.FORCEFIELD_MINIMIZATION_FAILED : 'force field structure refinement failed',
 78                      ConfGen.ReturnCode.FRAGMENT_LIBRARY_NOT_SET       : 'fragment library not available',
 79                      ConfGen.ReturnCode.FRAGMENT_CONF_GEN_FAILED       : 'fragment conformer generation failed',
 80                      ConfGen.ReturnCode.FRAGMENT_CONF_GEN_TIMEOUT      : 'fragment conformer generation timeout',
 81                      ConfGen.ReturnCode.FRAGMENT_ALREADY_PROCESSED     : 'fragment already processed',
 82                      ConfGen.ReturnCode.TORSION_DRIVING_FAILED         : 'torsion driving failed',
 83                      ConfGen.ReturnCode.CONF_GEN_FAILED                : 'conformer generation failed' }
 84    
 85    # create an instance of the default implementation of the Chem.Molecule interface
 86    mol = Chem.BasicMolecule()
 87    i = 1
 88    
 89    # read and process molecules one after the other until the end of input has been reached
 90    try:
 91        while reader.read(mol):
 92            # compose a simple molecule identifier
 93            mol_id = Chem.getName(mol).strip() 
 94
 95            if mol_id == '':
 96                mol_id = '#' + str(i) # fallback if name is empty
 97            else:
 98                mol_id = '\'%s\' (#%s)' % (mol_id, str(i))
 99
100            if not args.quiet:
101                print('- Generating 3D structure of molecule %s...' % mol_id)
102
103            try:
104                # generate 3D structure of the read molecule
105                status = gen3DStructure(mol, struct_gen) 
106
107                # check for severe error reported by status code
108                if status != ConfGen.ReturnCode.SUCCESS:
109                    if args.quiet:
110                        print('Error: 3D structure generation for molecule %s failed: %s' % (mol_id, status_to_str[status]))
111                    else:
112                        print(' -> 3D structure generation failed: %s' % status_to_str[status])
113                else: 
114                    # enforce the output of 3D coordinates in case of MDL file formats
115                    Chem.setMDLDimensionality(mol, 3)
116
117                    # output the generated 3D structure                    
118                    if not writer.write(mol):   
119                        sys.exit('Error: writing 3D structure of molecule %s failed' % mol_id)
120                        
121            except Exception as e:
122                sys.exit('Error: 3D structure generation or output for molecule %s failed: %s' % (mol_id, str(e)))
123
124            i += 1
125                
126    except Exception as e: # handle exception raised in case of severe read errors
127        sys.exit('Error: reading molecule failed: ' + str(e))
128
129    writer.close()
130    sys.exit(0)
131
132if __name__ == '__main__':
133    main()

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