Source code:
@Grab(group='org.openscience.cdk', module='cdk-bundle', version='2.9')
import org.openscience.cdk.interfaces.*;
import org.openscience.cdk.io.*;
import org.openscience.cdk.ringsearch.*;
import org.openscience.cdk.io.IChemObjectReader.Mode;
import org.openscience.cdk.*;
import java.io.File;
reader = new MDLV2000Reader(
new File("data/azulene.mol").newReader(),
Mode.STRICT
);
azulene = reader.read(new AtomContainer());
ringset = new AllRingsFinder().findAllRings(azulene, 5)
println "Number of rings: $ringset.atomContainerCount"
Output:
Number of rings: 1