Asymptote

Next time please post your .asy file and vector graphics (eps/pdf/svg not png) output.

The manual and gallery illustrate lots of ways to restrict the elements of the data arrays that should be graphed. For example:

1. Use the bool3[] cond argument.
2. Manually prune the data.
3. Use the crop argument of xlimits/ylimits (see the commented lines in loggraph.asy).