# Grouped Select Match

### Description
Given list of `[OBJ,OBJ]` pairs, these are assumed to be the result of a mapping operation, with the first and second columns identifying the `Source` and `Target` of such mappings, respectively.
This block selects the best (most likely) match for each OBJ in a column and for each group, if there are multiple candidates for a match. 
With the `Group on` parameter, the column to group on can be selected. All other pairs in the input will be discarded.

If `Group on = Target` then the best match is found for every group that is identified by:
(`Target`, the group `Source` belongs to).

If `Group on = Source` then the best match is found for every group that is identified by:
(`Source`, the group `Target` belongs to).

### Input
- `MAPPING [OBJ,OBJ]`: the candidate matches
- `GROUPS [OBJ,OBJ]`: map of each object (first column) to a group identifier (second column)
### Output
- `RESULT [OBJ,OBJ]`: the best match for every item in the `Grouped on` column.

### Parameters
- `Group on`: whether to group on the first column (`Source`) or the second column (`Target`).
- `Method`: how to select the best match
  - `Highest score`: for each group, select the match with highest score