User Request – Disable Limiting Region

The other week a user of ggtern ran into a problem where they wanted to use the limit_tern(...) functionality, however there were a few marginal points / paths that extended beyond the limiting region. Under normal circumstances, the standard ggtern behaviour is to strip these points, which can interfere with the desired outcome if they are part of a continuous path or polygon etc…

This is best demonstrated with an example:

Which produces the following output:

plot of chunk unnamed-chunk-2

It is clear in the above that the tail ends get truncated, where truthfully they should flow over the boundaries of the plot region. There is a way to suppress this behaviour, which is to modify an internal global option, tern.discard.external, as follows:

Which produces the following output, noting that the tails (top and right apex corners) now extend beyond past the limiting plot region.

plot of chunk unnamed-chunk-2

Needless to say that this feature should be used on a discretionary basis, in very specific situations where a minor overflow can be tolerated.

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  1. F. Valverde

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