Add option to pass coordinates to the grid method #326

santisoler · 2021-05-19T19:57:08Z

Allow the grid method of BaseGridder to take the coordinates of the
preexisting grid either as 2d arrays (meshgrid) or as 1d arrays. Raise
a FutureWarning if the spacing, shape or region arguments are passed,
since they will be removed in Verde v2.0.0. Write a new meshgrid_from_1d
function that creates a meshgrid out of 1d horizontal arrays, but also checks
if they have a single dimensions and supports for passing extra coordinates as
2d-arrays.

This PR is an evolution of #285, so #285 should be closed if this PR is merged.

Reminders:

Run make format and make check to make sure the code follows the style guide.
Add tests for new features or tests that would have caught the bug that you're fixing.
Add new public functions/methods/classes to doc/api/index.rst and the base __init__.py file for the package.
Write detailed docstrings for all functions/classes/methods. It often helps to design better code if you write the docstrings first.
If adding new functionality, add an example to the docstring, gallery, and/or tutorials.
Add your full name, affiliation, and ORCID (optional) to the AUTHORS.md file (if you haven't already) in case you'd like to be listed as an author on the Zenodo archive of the next release.

Start drafting the addition of an optional coordinates argument to the grid method of the BaseGridder. It would allow use to predict on preexisting grids and obtain a xr.Dataset as output. Add a new example that passes the coordinates of a preexisting grid to a Chain with a Spline inside. Write a new meshgrid_from_1d function that creates a meshgrid out of 1d horizontal arrays, but also checks if they have a single dimensions and supports for passing extra coordinates as 2d-arrays.

verde/base/base_classes.py

… allow-coords-in-grid

Rename variable to avoid overriding the grid_coordinates function

leouieda

Left a few suggestions but nothing major. Really good work, as always 🙂

examples/predict_on_grid_coordinates.py

leouieda · 2021-07-20T08:30:26Z

examples/predict_on_grid_coordinates.py

+coordinates = (easting, northing)
+
+# Use the .grid() method to predict on the grid coordinates
+grid = gridder.grid(coordinates)


Using coordinates for the grid coordinates is going to be confusing. Probably best to use coordinates for data coordinates and grid_coordinates for grid coordinates throughout the code and examples.

I agreed at first, but then I found that we already use grid_coordinates for the function that creates the coords of a regular grid. Should we use a different name for the coordinates argument? Maybe grid_coords?

Yeah, you're right. grid_coords is reasonable I guess

I'm having second thoughts on this. Is really an issue of having coordinates argument on methods like predict and in grid while the requirements are slightly different? I think having a common coordinates arguments for methods and functions in Verde is a feature and not an issue:

I can autocomplete on every call by just typing coor<TAB> (with grid_coords it wouldn't work, I would need to delete and start typing gri).

On some places it doesn't mind if the passed coordinates are scattered or regular gridded (forward modelling in Harmonica for instance). So those cases would be an exception where coordinates should be used, although grid coordinates could also be passed.

On the specific BaseGridder we would have two methods that do almost the same but for different kind of coordinates: predict for scattered coordiantes, grid for grid coordinates. I think that difference is sufficient for differentiating the distribution of the coords.

One last argument, if we use grid_coords, an simple example of the grid method would look like:

grid = gridder.grid(grid_coords=...)

I can see myself struggling to read that line out loud when teaching.

What do you think?

You're absolutely right. Typing spline.grid(grid_coords...) is awkward. So here is a proposal:

Function arguments are coordinates unless you need to specify 2 sets (like distance_mask).

For examples: coordinates means data coordinates and grid_coords means grid coordinates since there will usually be the 2 sets and we'll need to distinguish between them. That way the call could be spline.grid(coordinates=grid_coords... or spline.grid(coordinates=vd.grid_coordinates...).

Now that I write this, I'm not entire happy with requiring giving coordinates all the time. But I don't know what else to do. I would want to write some examples using this syntax to see how it feels but my feeling is that it will be a bit of a blow to general usability.

I agree with the two points above. Just a reminder for the future: don't underestimate the old design decisions, there might be a reason why we took that road even if we don't remember it.

Feel free to try it out on examples, there's no rush for this PR. If we are going to change the default behavior of the base class for Verde gridders, it's good to put a lot of thinking into it.

On the note about passing coordinates every time I think we are already doing it, but hiding it through the spacing, shape, region, projection arguments. So the grid method currently does two things: creates a set of grid coordinates and predicts on them. I would like to split it in two:

Leave the coordinate generation to the user. This way they can corroborate that the grid is the right one before they have to wait until the prediction is carried out. Or they can just use a predefined grid and skip this step.

Use the grid method to predict on the given coordinates. It should also project the coords before running the prediction if any projection is passed. This simplifies the usage of the grid method, makes it easier to generalize to gridders like EQL with easting, northing and height (they can be part of the coordinates directly) and makes it easier to understand what the projection callback will be used for (I always struggle to think if the projection is applied before the prediction or after it and which coordinates should I use for region and spacing).

Finally, I think this new grid method will be doing a single task, and doing it well 😁 .

verde/base/base_classes.py

verde/utils.py

Co-authored-by: Leonardo Uieda <leouieda@gmail.com>

We will change every gridding example so they predefine grid coordinates and pass them as the `coordinates` argument.

santisoler · 2021-08-11T17:37:22Z

@leouieda I've added a FutureWarning if the region, spacing or shape arguments are passed, in agreement with our last Developer Meeting. Let me know if we need to change something else here. After this PR is merged, we should start changing the current examples so they create the grid coordinates right before calling the grid method.

leouieda

Just some small comments on the docstring. Otherwise, this looks good to me 👍🏽

verde/base/base_classes.py

leouieda · 2021-08-27T06:52:55Z

verde/base/base_classes.py

+            should be a 2d dimensional grid with a shape of ``(northing.shape,
+            easting.shape)``. The arrays could either be Numpy arrays or
+            :class:`xarray.DataArray`s. If ``coordinates`` are passed, no
+            ``region``, ``shape`` nor ``spacing`` is needed.


I would remove the part about the extra coordinates since in Verde itself they are ignored. Other libraries may implement this differently as well so it’s best to leave unspecified.

The arrays could be all sorts of things (pandas Series, cupy, dask, etc) so saying “array” is best without needing to specify types.

“If coordinates are passes, region, shape, and spacing are ignored.”

Let me know if you like it better now.

Co-authored-by: Leonardo Uieda <leouieda@gmail.com>

santisoler added 2 commits May 19, 2021 16:53

Merge branch 'master' into allow-coords-in-grid

1a95532

santisoler commented May 26, 2021

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verde/base/base_classes.py Outdated Show resolved Hide resolved

santisoler added 7 commits May 26, 2021 09:08

Fix typo

af3babb

Add test functions

84ba68c

Merge branch 'allow-coords-in-grid' of github.com:fatiando/verde into…

68c6820

… allow-coords-in-grid

Raise error if coordinates and region are passed

d0067c3

Rename grid_coordinates variable to grid_coords

3edb79a

Rename variable to avoid overriding the grid_coordinates function

Test grid method with coordinates as 1d arrays

1434206

Use CheckerBoard on the example and rename its file

8ce72d0

santisoler changed the title ~~WIP Add option to pass coordinates to the grid method~~ Add option to pass coordinates to the grid method Jun 17, 2021

Fix linting error

2682c1b

santisoler mentioned this pull request Jun 17, 2021

WIP Add predict_onto_grid method to BaseGridder #285

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leouieda requested changes Jul 20, 2021

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santisoler and others added 5 commits August 2, 2021 09:18

Improve error message

4fe7e8c

Co-authored-by: Leonardo Uieda <leouieda@gmail.com>

Move coordinates argument to the end

b7add8a

Rename func to get_ndim_horizontal_coords and extend docs

1e614ee

Remove example for this new feature

e196bee

We will change every gridding example so they predefine grid coordinates and pass them as the `coordinates` argument.

Raise FutureWarnings after spacing, shape or region arguments

914097c

santisoler requested a review from leouieda August 11, 2021 17:35

leouieda approved these changes Aug 27, 2021

View reviewed changes

santisoler and others added 4 commits August 27, 2021 13:17

Extend docstring of grid method

f929efe

Co-authored-by: Leonardo Uieda <leouieda@gmail.com>

Fix docstring for coordinates in grid method

0107912

Wrap long line created by GitHub review

a5fbbbf

Merge branch 'master' into allow-coords-in-grid

ee26e8b

leouieda merged commit eb636e3 into master Nov 3, 2021

leouieda deleted the allow-coords-in-grid branch November 3, 2021 10:39

santisoler mentioned this pull request Apr 23, 2022

Prepare project_grid for the future grid method in Verde gridders #363

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santisoler mentioned this pull request May 19, 2022

Ditch soon-to-be deprecated args of equivalent sources grid method fatiando/harmonica#311

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Add option to pass coordinates to the grid method #326

Add option to pass coordinates to the grid method #326

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Add option to pass coordinates to the grid method #326

Add option to pass coordinates to the grid method #326

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