A attempt to make a query in the CDMS through the VAMDC interface

vamdc_query.py

# vamdc_query.py -- Search for lines in the CDMS through VAMDC

import urllib2
import xml.etree.ElementTree as ET

species = "CO"
fmin = 109e9
fmax = 111e9
einstein = - 1
energy = -1

base_url = "http://cdms.ph1.uni-koeln.de/cdms/tap/sync?LANG=VSS2&REQUEST=doQuery&FORMAT=XSAMS&QUERY="
c = 299792458.0 #m/s

wlmin = c / fmax * 1e9 # Angstroms
wlmax = c / fmin * 1e9

# Construct the query in VSS2 format. For details, see
# http://vamdc-standards.readthedocs.org/en/latest/queryLanguage/vss2.html

vss2_query = "select * where (RadTransWavelength >= %e and RadTransWavelength >= %e" % (wlmin, wlmax)
if energy != -1:
    vss2_query += "and upper.StateEnergy <= %e" % energy
if einstein != -1:
    vss2_query += "and RadTransProbabilityA <= %e" % einstein
vss2_query += ")"
if species != 'All':
    vss2_query += "and (MoleculeStoichiometricFormula='%s')" % species # isotologues?
    vss2_query = urllib2.quote(vss2_query)
    
# Get the results in VAMC-XSAMS format.

tap_url = base_url + vss2_query
try:
    response = urllib2.urlopen(tap_url)
except Exception, error:
    raise Exception, "Could not connect to database: %s" % error

# Parse the results
# We need to get 1) a species list with their corresponding tags
# and 2) the list of lines
# How to do this?

import xml.etree.ElementTree as ET
tree = ET.parse(response)
root = tree.getroot()

response.close()