Child dict refactor (also removes anytree dependency) (#76)

* draft implementation of a TreeNode class which stores children in a dict

* separate path-like access out into mixin

* pseudocode for node getter

* basic idea for a path-like object which inherits from pathlib

* pass type checking

* implement attach

* consolidate tree classes

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* passes some basic family tree tests

* frozen children

* passes all basic family tree tests

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* copied iterators code over from anytree

* get nodes with path-like syntax

* relative path method

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* set and get node methods

* copy anytree iterators

* add anytree license

* change iterator import

* copy anytree's string renderer

* renderer

* refactored treenode to use .get

* black

* updated datatree tests to match new path API

* moved io tests to their own file

* reimplemented getitem in terms of .get

* reimplemented setitem in terms of .update

* remove anytree dependency

* from_dict constructor

* string representation of tree

* fixed tree diff

* fixed io

* removed cheeky print statements

* fixed isomorphism checking

* fixed map_over_subtree

* removed now-uneeded utils.py compatibility functions

* fixed tests for mapped dataset api methods

* updated API docs

* reimplement __setitem__ in terms of _set

* fixed bug by ensuring name of child node is changed to match key it is stored under

* updated docs

* added whats-new, and put all changes from this PR in it

* added summary of previous versions

* remove outdated ._add_child method

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

README.md

@@ -5,8 +5,8 @@ This aims to create the data structure discussed in [xarray issue #4118](https:/
 
 
 The approach used here is based on benbovy's [`DatasetNode` example](https://gist.github.com/benbovy/92e7c76220af1aaa4b3a0b65374e233a) - the basic idea is that each tree node wraps a up to a single `xarray.Dataset`. The differences are that this effort:
-- [Uses a NodeMixin from anytree](https://github.com/TomNicholas/datatree/issues/7) for the tree structure,
-- Implements path-like and tag-like getting and setting,
+- Uses a node structure inspired by [anytree](https://github.com/TomNicholas/datatree/issues/7) for the tree,
+- Implements path-like getting and setting,
 - Has functions for mapping user-supplied functions over every node in the tree,
 - Automatically dispatches *some* of `xarray.Dataset`'s API over every node in the tree (such as `.isel`),
 - Has a bunch of tests,
@@ -17,5 +17,5 @@ You can create a `DataTree` object in 3 ways:
 1) Load from a netCDF file (or Zarr store) that has groups via `open_datatree()`.
 2) Using the init method of `DataTree`, which creates an individual node.
   You can then specify the nodes' relationships to one other, either by setting `.parent` and `.chlldren` attributes,
-  or through `__get/setitem__` access, e.g. `dt['path/to/node'] = xr.Dataset()`.
+  or through `__get/setitem__` access, e.g. `dt['path/to/node'] = DataTree()`.
 3) Create a tree from a dictionary of paths to datasets using `DataTree.from_dict()`.

ci/doc.yml

@@ -6,7 +6,6 @@ dependencies:
   - python>=3.8
   - xarray>=0.20.2
   - netcdf4
-  - anytree
   - scipy
   - sphinx
   - sphinx-copybutton

ci/environment.yml

@@ -6,7 +6,6 @@ dependencies:
   - python>=3.8
   - xarray>=0.20.2
   - netcdf4
-  - anytree
   - pytest
   - flake8
   - black