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jonas-p / go-shp

Go library for reading and writing ESRI Shapefiles. Pure Golang implementation based on the ESRI Shapefile technical description.
MIT License
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Add WKT / WKB representation of geometry #39

Open tomplex opened 5 years ago

tomplex commented 5 years ago

This would make it a lot easier to use go-shp to interface with other libraries which implement geometry operations, like gogeos or orb.

fawick commented 5 years ago

What is the usecase that you want to solve with that?

go-shp is a library for reading the shapefile binary fileformat, converting the read geometries to WKT / WKB is a bit out of scope here. For precedence, are you aware of libraries (in other languages, maybe) that provide native WKT / WKB support for shape files?

I can understand the need to have a lingua franca for geometry data to ease the pain to glue together different libraries. I am just not sure that WKT / WKB would a be a good fit for go-shp. Maybe the answer would be a subpackage?

tomplex commented 5 years ago

Thanks for responding!

The general use case is, I have a shape file that I want to open, read geometry from, and process somehow. I don't want to write my own geometry processing algorithms because there already exist many implementations like those mentioned above, which can read their own geometry objects from wkt / wkb, but often dont implement reading of binary formats like shp or TAB - so we need to turn to libraries like this to do so.

We have "well known" formats for this reason, so that packages can support them - a relatively small interface - and easily interoperate with other packages which deal with geometry. Especially in a strongly typed language like Go, having a different implementation of geometry for every package doesn't help anything if none of them can talk to each other.

As for other languages, in Java / Geotools, you can convert a geometry read from shapefile to wkt using a factory (ugh) or using the toString() method - which would be a nice fit for Golangs Stringer interface. In python, the default for the Fiona/Shapely packages is geojson, which is a good fit for Python because the dicts are basically valid json as is. You could argue that they work so well together because they're written by the same guy - a valid point - but it's a pleasure to work with geometry in python because all the disparate tools work together easily.

All that said, I'd be very happy to take a shot at it and submit a PR for this package with an implementation that we can iterate on, if you would be receptive to it! I think a subpackage which has conversion functions could be a great solution, and a step in a direction towards easier interoperability.

Thanks for your time! Tom