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/2176#issuecomment-392138523,https://api.github.com/repos/pydata/xarray/issues/2176,392138523,MDEyOklzc3VlQ29tbWVudDM5MjEzODUyMw==,12307589,2018-05-25T18:11:55Z,2018-05-25T18:11:55Z,CONTRIBUTOR,"Thank you for the input everyone, this discussion has been very useful! Closing this issue.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,325810810
https://github.com/pydata/xarray/issues/2176#issuecomment-391800114,https://api.github.com/repos/pydata/xarray/issues/2176,391800114,MDEyOklzc3VlQ29tbWVudDM5MTgwMDExNA==,12307589,2018-05-24T17:41:27Z,2018-05-24T17:41:27Z,CONTRIBUTOR,"@dopplershift That's a good point. It's pretty trivial to create a `sympl.DataArray` from an `xarray.DataArray`, so perhaps I should be using a decorator that will convert `xarray.DataArray` to `sympl.DataArray` whenever one is passed into a `sympl` call. This would be similarly easy to do in `metpy`. One could also write a function to convert `Dataset` into one that contains unit-aware `DataArray` objects, or an `open_dataset` that calls `xarray.open_dataset` and then does such a conversion, though I'd wonder if certain `Dataset` calls (e.g. `mean`) might undo such a conversion.
In `sympl` our main concerns are unit checking at the boundary of components and in properly converting units when time stepping or adding outputs of components together. Maybe `sympl` should only be using this `DataArray` subclass internally, with type conversions or wrapping when taking `DataArray`s into and out of its methods? That would solve a lot of our problems.
`unyt` may be a better choice than `pint` for MetPy. Like I said in Sympl we don't use `pint` for unit information storage, only for conversion and arithmetic, so whether it uses an ndarray subclass doesn't apply for us.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,325810810
https://github.com/pydata/xarray/issues/2176#issuecomment-391542922,https://api.github.com/repos/pydata/xarray/issues/2176,391542922,MDEyOklzc3VlQ29tbWVudDM5MTU0MjkyMg==,12307589,2018-05-24T00:10:29Z,2018-05-24T00:10:29Z,CONTRIBUTOR,"@shoyer that notation might work, thanks for pointing it out! Maybe we can think of a more natural name for the accessor (""with_units""? ""keep_units""? ""uarray""? ""u""?). I find the ""storage"" of units as a string in attrs to be much cleaner than any other implementation I've seen so far (like implementations that have a unit container over an underlying array, or an array of unit-aware objects). It has the added benefit that this is how units are conventionally stored in netCDF files. I don't think it's necessary to use a class other than ndarray for data storage.
@kmpaul the main reason I stayed away from `cf_units` is that I had bad experiences trying to get it to build with its dependencies in the past. Particularly it's an issue that it depends on the Udunits C library, which requires MinGW to install on Windows and has generally been a headache for me. I'd much prefer a pure Python unit handling implementation. For Sympl, we don't care so much about time units, because time is stored using `datetime` objects (potentially from the `cftime` package for alternate calendars). This is also the way that time units are conventionally stored in `xarray`, once decoded.
It may make sense for us to use some kind of stand-alone unit-aware DataArray implementation. I'd just need to be convinced that yours is well-designed, thoroughly tested, and easy to install with pip. The main things concerning me about `PhysArray` are 1) As a container rather than subclass, it does not implement many of the methods of `DataArray` and 2) There are a few design choices I don't understand, like why `calendar` is always a property of a `PhysArray` even when it isn't storing a time, why `cftime` objects aren't used instead of units to manage time, and why the `positive` attribute is important enough for `PhysArray` to manage (I've never seen it in any data I've used, and it's easy to check if a `DataArray` is all positive or negative with a function call). We could discuss these by e-mail if you like (it's my username at uw.edu). Other possibilities are that I'll take the implementation we come up with and give it its own package, or that we'll collaborate on such a package.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,325810810
https://github.com/pydata/xarray/issues/2176#issuecomment-391443258,https://api.github.com/repos/pydata/xarray/issues/2176,391443258,MDEyOklzc3VlQ29tbWVudDM5MTQ0MzI1OA==,12307589,2018-05-23T18:03:27Z,2018-05-23T18:03:27Z,CONTRIBUTOR,"For reference, here are some of the sort of methods I've been adding that aren't currently in `sympl`:
def multiply(self, other):
if isinstance(other, xr.DataArray):
result = self._dataarray * other
result.attrs['units'] = multiply_units(self._dataarray.attrs['units'], other.attrs['units'])
else:
result = self._dataarray * other
result.attrs['units'] = self._dataarray.attrs['units']
return result
def divide(self, other):
print(self._dataarray, other)
if isinstance(other, xr.DataArray):
result = self._dataarray / other
result.attrs['units'] = divide_units(self._dataarray.attrs['units'], other.attrs['units'])
else:
result = self._dataarray / other
result.attrs['units'] = self._dataarray.attrs['units']
return result
def add(self, other):
result = self._dataarray + other.sympl.to_units(self._dataarray.attrs['units'])
result.attrs['units'] = self._dataarray.attrs['units']
return result
def subtract(self, other):
result = self._dataarray - other.sympl.to_units(self._dataarray.attrs['units'])
result.attrs['units'] = self._dataarray.attrs['units']
return result","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,325810810