Class MergeStage

    UserDict.UserDict --+        
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UserDict.IterableUserDict --+    
                            |    
                  stage.Stage --+
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                               MergeStage

Stage for merging up to 100 Glide output files with 'glide_ensemble_merge'.
The input files can be either PV or LIB, and have to be sorted by
GlideScoreglide.  The output file will also be sorted, and the GlideScores
can be offset by a specified value for each input file.

The keywords specific to this stage are...

    NREPORT     Save only the top NREPORT poses.  The default is 0, which
                retains all poses.

    MAXPERLIG   Retain at most MAXPERLIG poses for each ligand
                (determined by the structure title).  The default is 1.
                Use 0 to retain all poses.

    OFFSETS     List of GlideScore offsets (float) to be applied to the
                input structures. First item in the list is the offset
                for the first input, second is for second input, etc.
                If not specified, all are defaulted to 0.0.
    
    MARKERS     List of string lables for each receptor. Each ligand will
                be marked by this value depending on which input set it
                originated from.
    

    Not implemented yet:

    ONOFFS      List of boolean values for each receptor; whether it is an
                on target (default) or off target. Ev:81291
    
    SELECTIVITY_THRESHOLD  The minimum energy difference between on-target
                           and off-target GlideScore that is required in 
                           order to keep this ligand.




The stage takes up to 100 input structure file sets (PV or LIB) and
generates a single output pose file.