AddDCNlabelingScheme.py

#!/nmr/programs/python/bin/python2.5
"""
AddDCNlabelingScheme.py reads in a cara repository file and modifies
the residue-type definitions to include a labeling scheme with N15,C13,H2.
A labeling scheme called 'DCN' is added for this purpose.
"""

import sys
sys.path.append('/nmr/programs/python/')
import xml.etree.ElementTree as ET
from xml.etree.ElementTree import Element, SubElement
import string

def main():
    if len(sys.argv) not in [3,4]:
        print '==============================================================================='
        print 'AddDCNlabelingScheme.py reads in a cara repository file and modifies the'
        print 'residue-type definitions to include a labeling scheme with 13C,15N, and 2H.'
        print ''
        print 'A labeling scheme called \'DCN\' is added for this purpose.'
        print ''
        print 'Usage: AddDCNlabelingScheme.py infile.cara outfile.cara'
        print 'Number of arguments given: %d'%(len(sys.argv)-1)
        print 'An optional third argument names which project to modify, if'
        print 'there is more than one project in a repository. '
        print '=============================================================================='
        return

    infile = sys.argv[1]
    outfile = sys.argv[2]

    if infile == outfile:
        print '\nPlease do not overwrite your original file. Try again.\n'
        return

    tree = ET.parse(infile)
    root = tree.getroot()
    projects = root.findall('project')

# Select a project according to command-line input, defaulting to the first project

    if len(sys.argv) == 4:
        projectName = sys.argv[3]
        project = getProject(projectName,projects)
        if not project:
            print 'No project found with name \"%s\".'%projectName
            return
    else:
        project = projects[0]
        if not project:
            print 'No project found.'
            return

# Find existing schemes & make a new one by incrementing the highest existing ID number

    library = root.find('library')
    schemes = library.findall('scheme')
    numSchemes = len(schemes)
    if numSchemes > 0:
        schemeIDs = [int(scheme.get('id')) for scheme in schemes]
        schemeIDs.sort()
        newIDnum = schemeIDs[numSchemes-1]+1
        newID = '%d'%newIDnum
    else:
        newID = '1'
    newscheme = SubElement(library,'scheme')
    newscheme.attrib['id'] = newID
    newscheme.attrib['name'] = 'DCN'#%newID

# Modify residue-type

    residueTypes = library.findall('residue-type')
    for residueType in residueTypes:
        atoms = residueType.findall('atom')
        for atom in atoms:
            if atom.get('name')[0]=='H' and atom.get('name')!='H':
                newscheme = SubElement(atom,'scheme')
                newscheme.attrib['id'] = newID
                newscheme.attrib['type'] = 'H2'
                    
                
    tree.write(outfile)
    
main()