Specifying nearneighbor -S, unit not understood? about gmt HOT 12 CLOSED

nearneighbor [INFORMATION]: Your distance unit (e) implies geographic data; -fg has been set.

Well, I think explains the different behavior.

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Ok, but shouldn't this be set with both -S200e and -S200?

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The first one is for geographic input data (long and lat). The second for Cartesian (X and Y).

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Alright. Thanks Esteban.

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Maybe the -S docs should say -Ssearch_radius[unit] to indicate that the unit is optional (relevant if your input is geographic coordinates).

I get confused since it looks like the unit is mandatory. Since my input data is in meters, I use the unit e. But since its already projected, this is wrong.

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The issue here is that saying -Se is the default is false. That message comes from a generic text that is imported into all modules that use units. The default -S for nearneighbor is the data units, and probably converted to meters when it knows input is geogs but likely not if it doesn't know that. So, yes, a confusing situation.

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So, yes, a confusing situation.

Appreciate you saying that.

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• So for nearneighbor's -S, maybe we could:

  • Change -Ssearch_radius to -Ssearch_radius[unit]. Since the unit is not mandatory, after all. Might even be an error to use a unit, if the data is (already) projected.
  • Change "Append the distance unit (see [Units])." --> "Append the distance unit if input is geographical (see [Units]).", or something like that.

  Both of these to help the user understand that if the data is already projected, no unit is to be appended.

• It puzzles me that the generic Unit text says meter is [Default unless stated otherwise]. As @joa-quim stated above (and I experienced), -S200 is not at all the same as -S200e. Maybe this is special for nearneighbor.

I can do the changes if you agree.

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#8374 deals with the docs. I’m not able to make any changes for the cli, since this involves messing with the souce code.

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I've committed the C changes directly to master.

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Thanks!

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