html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/2473#issuecomment-434627405,https://api.github.com/repos/pydata/xarray/issues/2473,434627405,MDEyOklzc3VlQ29tbWVudDQzNDYyNzQwNQ==,35968931,2018-10-31T09:58:05Z,2018-10-31T09:58:05Z,MEMBER,"#2482 has now been merged which means that I can get the behaviour I want by using globally-permanent attrs to store arbitrary objects, and using accessors to attach methods to datasets.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,367763373
https://github.com/pydata/xarray/issues/2473#issuecomment-429429134,https://api.github.com/repos/pydata/xarray/issues/2473,429429134,MDEyOklzc3VlQ29tbWVudDQyOTQyOTEzNA==,35968931,2018-10-12T19:05:24Z,2018-10-12T19:05:59Z,MEMBER,"I realised I'm massively overcomplicating this, I think all I need is the existing accessor functionality, and for attrs to always be preserved in order to get the behaviour I want. Therefore once #2482 is merged then I should be able to close this.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,367763373
https://github.com/pydata/xarray/issues/2473#issuecomment-428179704,https://api.github.com/repos/pydata/xarray/issues/2473,428179704,MDEyOklzc3VlQ29tbWVudDQyODE3OTcwNA==,35968931,2018-10-09T12:52:30Z,2018-10-09T14:53:30Z,MEMBER,"Sorry for the triple comment, but I could also do this:
If I do this:
```python
@xr.register_dataset_accessor('bout')
class BoutAccessor(object):
def __init__(self, ds_object):
self._data = ds_object
def set_options(self, options):
self.options = options
@register_dataset_accessor('storm')
class StormAccessor(BoutAccessor):
def __init__(self, ds_object):
super().__init__(ds_object)
def special_storm_plot()
special_storm_plot(self._data, self.options)
```
then I can have BOUT-specific attributes and methods stored via the bout accessor, all of which are inherited by the more-specific storm accessor
```python
ds = collect_data(path)
options_obj = get_options(path)
ds.storm.set_options(options_obj) # access inherited methods from the bout accessor to store arbitrary extra data
ds.storm.special_storm_plot() # use data from the bout accessor when calling more-specific methods form the storm accessor
```
However then my attached objects don't survive the calling of xarray methods:
```python
ds.storm.extra_info = 'options'
new_ds = ds.isel(t=-1)
print(new_ds.storm.extra_info) # AttributeError: 'StormAccessor' object has no attribute 'extra_info'
```
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,367763373
https://github.com/pydata/xarray/issues/2473#issuecomment-428170843,https://api.github.com/repos/pydata/xarray/issues/2473,428170843,MDEyOklzc3VlQ29tbWVudDQyODE3MDg0Mw==,35968931,2018-10-09T12:21:53Z,2018-10-09T12:21:53Z,MEMBER,"Or alternatively I suppose I could just store my options as an attribute on the accessor:
```python
ds = collect_data(path)
ds.bout.options = options_obj
# Now I have an object which stores all the data I want
print(ds.bout.options)
```
That seems to be what I should have tried first.
In that case would it be possible to have multiple accessors, one for the core bout functionality and others for extensions for even-more-specific users? i.e an accessor for a code called Storm which is based on BOUT++:
```python
print(ds) # xarray dataset
print(ds.bout.options) # BOUT-specific extra information
print(ds.storm.special_storm_plot()) # storm-user-group-specific method
```
Can an accessor inherit from another accessor class?
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,367763373
https://github.com/pydata/xarray/issues/2473#issuecomment-428152588,https://api.github.com/repos/pydata/xarray/issues/2473,428152588,MDEyOklzc3VlQ29tbWVudDQyODE1MjU4OA==,35968931,2018-10-09T11:10:46Z,2018-10-09T11:10:46Z,MEMBER,"> Accessors should only accept one argument, which is an xarray.Dataset.
Ah - I misunderstood how they work, if I do this:
```python
@xr.register_dataset_accessor('bout')
class BoutDataset(object):
def __init__(self, ds_object):
self.data = ds_object
def plot_tokamak():
plot_in_bout_specific_way(self.data, self.extra_data)
```
then I can successfully use it like this:
```python
ds = collect_data(path)
ds.bout.plot_tokamak()
print(ds.bout.data)
```
Thanks!
> What does your extra_data look like? Would it be possible to put it into xarray in the form of coordinates or attributes?
My `extra_data` is a nested-dictionary-like object containing everything in the simulation input file. This I can store in the attributes dictionary (that's what I'm doing at the moment), but I'm still interested in the problem of attaching arbitrary objects because because losing the attributes on operations is annoying and I envisage either myself or other users of the code wanting to store more complicated structures in the future. (For example an [xgcm grid object](https://xgcm.readthedocs.io/en/latest/api.html#xgcm.Grid))
Also the philosophy of the BOUT framework encourages each group of users to add their own functionality depending on what exactly they are solving. Some kind of base `BoutDataset` class which could then be further subclassed to add more specific functionality would fit best with this system. Would it be a terrible idea to subclass `xr.Dataset` into a `BoutDataset`, then decorate every inherited method by looping over them so that my extra attached objects are dealt with appropriately (maybe[ like this](https://stackoverflow.com/questions/6307761/how-can-i-decorate-all-functions-of-a-class-without-typing-it-over-and-over-for))? Would that not in theory give me the whole API of xarray while allowing me to attach arbitrary objects and methods to my class, and allowing further subclassing if desired?
(Sorry if this is too far off the topic of xarray, feel free to close it if you think this is not going to be relevant to any of the rest of the community.)","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,367763373