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I have an Origin-Destination table like this

Origin Destination Value
A B 10
B A 100
A C 120
...

For all the locations A, B, C... I have another table indicating their location (Lat and Lon)

Is there any way to draw two separate lines between A and B so that I can visualize the directionality and distinguish the flow volume between these two places?

Thanks!

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Some of the answers given to the related question at gis.stackexchange.com/questions/5204/… might naturally solve this because the arcs they draw are asymmetrical. Because that is somewhat of an accidental feature of these solutions, they ought to be considered work-arounds rather than primary answers to your question, but perhaps they might be helpful in some cases. – whuber♦ Feb 20 at 20:39
@whuber Thanks for your suggestions. I was thinking a way to solve this: 1) Define a function DrawArcBetween(Origin, Destination, arc) 2) Define a Hashset<Destination,Origin> 3) If the destination, origin pair can be found in the Hashset, take the negative of the arc. Don't know if there would be simpler way to solve this... – Seen Feb 20 at 20:49
There are simpler ways. For instance, define an asymmetric arc-drawing function. (Mathematica does this by default for directed graphs, incidentally.) For example, to draw an arc from A to B, first jog a little to the left at A, head towards the left of B, then jog (towards the right) back to B at the end. That algorithm when applied from B to A will produce a different parallel arc between A and B. I have illustrated this in an answer at stats.stackexchange.com/questions/48467/…. – whuber♦ Feb 20 at 21:01
Are you trying to do this in ArcGIS or R? – Andy Feb 20 at 22:11
@Andy R should be fine for me. – Seen Feb 20 at 22:25
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