Support more than one set of data being expressed in one graph

[marimeireles]

You should be able to do an N number of queries and get each one of these results expressed in one graph with them overlaying each other.
A way to achieve this is allow the user to choose which column they want to show to each graph...
The current syntax is: %XVEGA_PLOT X_FIELD Level Y_FIELD Hitpoints MARK area WIDTH 100 HEIGHT 200 <> SELECT Level, Hitpoints FROM players
Could be changed for something like: %XVEGA_PLOT COLUMN Character VALUE Wizard MARK area COLOR red, VALUE Warrior COLOR blue MARK line X_FIELD Level Y_FIELD Hitpoints WIDTH 100 HEIGHT 200 <> SELECT Character, Level, Hitpoints FROM players

[marimeireles]

These should probably be renamed for the names the Vega API is using.
I think vega offers an API for having two graphs? Maybe it's possible to do with these offsets?

            // Fill in Position and Offset Properties
            serialize(j, x(), "x");
            serialize(j, x2(), "x2");
            serialize(j, width(), "width");
            serialize(j, height(), "height");
            serialize(j, y(), "y");
            serialize(j, y2(), "y2");
            serialize(j, xOffset(), "xOffset");
            serialize(j, x2Offset(), "x2Offset");
            serialize(j, yOffset(), "yOffset");
            serialize(j, y2Offset(), "y2Offset");

[marimeireles]

Character	Level	HP
Wizard	1	10
Wizard	2	15
Warrior	1	40
Warrior	3	200

This would generate two lines in the graph visualization.