grdcontour - Plotting of open/closed contours and dumping of closed contours

[anbj]

This is a copy of a feature request from the old website (http://gmt.soest.hawaii.edu/issues/914). I'm particularly interested in 2.

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Some suggestions for an even better grdcontour:

1. Add an option for plotting only open or closed contours (sometimes, you want to focus only on the closed contours or only on the open contours)
2. (Related to the existing ability of dumping contours based on whether they are closed or open, -D%c) Add an option to distinguish between closed contours based on whether they are closed in a downward or upward direction (not talking about an algorithm for finding locate valleys and hilltops) - e.g. dump closed contours as data line segments into two separate files; for example C_upwards.gmt and C_downwards.gmt. GMT is obviously capable of this - ref. the -T option in grdcontour.

[anbj]

Lack of interest. This is an old one. Closing.