Converting OSGB36 coordinates (Eastings and Northings) to WGS84 Lat Longs?

milhouse

Hi All,

I have a dataset with columns with Eastings and Northings in the Ordnance Survey OSGB36 National Grid (https://spatialreference.org/ref/epsg/27700/). I'd like to convert these to Latlongs (WGS84) and was wondering if there was a way to do that with a built in Dataiku function? I had a look at the coordinate reference system conversion processor and it looks like the input data needs to be in degrees. The OSGB data looks like this:

easting	northing
521508	193079
535379	180783
529701	170398
525312	178385

If not, does anyone have a reliable python (or other) script to do the conversion? I've done a bit of Googling but not found a definitive way of calculating it, and the maths is definitely beyond me.

Thanks!
Steven

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Operating system used: MacOS

HarizoR

Hi Steven,

There is an open-source Python package called convertbng that may suit your needs. You can install it using code environments and then leverage it in any of your Python code (recipes, notebooks, etc.).

Hope this helps!

Best,

Harizo

milhouse

Thanks Harizo! I'll read up the documentation on code environments, I've not used Python scripts in DSS yet, but this gives me the hint I needed!

Steven

milhouse

So I created a code environment and installed the convertbng module, and have confirmed that the module was successfully installed to the code environment. I believe this is set at the DSS level, not the project level?
When I return to my project, is there something I need to do to let it know which code environment it should use? I'm using a Python code step in a recipe to hopefully run the conversion, but when I try to import the module at the top of the python script and run it, I get the following error:

Python error : <type 'exceptions.ImportError'> : No module named convertbng.

Here's the code I tried to add:

import convertbng

def process(row):
  lonlat = convertbng.convert_lonlat([row['location_easting_osgr']],[row['location_northing_osgr']])
  return lonlat

Sorry if I've missed something obvious. I checked the following documentation pages:
https://doc.dataiku.com/dss/10.0/python/index.html
https://doc.dataiku.com/dss/10.0/code-envs/operations-python.html

Thanks,

Steven

milhouse

Ah, so I found that in the project settings there was a Code env selection option, and configured the environment I'd installed the module to. I was hoping at that point that my recipe step would recognise the module as being installed, but I still get the same error.

milhouse

And in case it helps anyone else, I found that if I checked the "Use a real Python process (instead of Jython)" that worked.

Manuel

Hi,

At the recipe level, in the advanced settings, you can also specify which code environment to use for that recipe alone. See the attached image.

I hope this helps.