I’m not sure I understand your question, but if you are looking at making the height of the bar based on I but the color of the bar a different color based on V, I have done this by using a standard chart component instead of the bar chart component, with the selection set to bar renderer.
Use scripting or your query to filter your single dataset into multiple data sets based on your value of V, where the dataset values for I that didn’t match V are set to 0. You can then set the color of each dataset to what you want (Red for R between 10-20, Blue for R between 20-30, etc.). Graph all of these items on the same X axis. In this way, it appears to be a single dataset being graphed, but each bar relates to the color desired.
Not sure if this is what you are looking for, but thought I would pass it along. I had a customer ask for their hourly production level to be color coded based on how close they were to target, and this is how I solved the issue.