Getting aggregated value across dimension members

Sorry, the post is not clear enough. Let's say we have a data model with a measure "score":
+-------+
| score |
+-------+
| 150 |
+-------+
Let's say there's also a dimension "signature" that we add to the custom visual afterwards. The dataview is now:
+-----------+-------+
| signature | score |
+-----------+-------+
| math | 50 |
+-----------+-------+
| biology | 50 |
+-----------+-------+
| english | 50 |
+-----------+-------+
The question is: assuming we have score by signature in the dataview already, is there a way to get the aggregate value (150) via the custom visuals API? we think not, but we'd like to get official confirmation.
Hopefully this is clear enough. Let me know