issues: 295621576

Code Sample, a copy-pastable example if possible

```python import numpy as np import xarray as xr n_times = 4; n_lats = 10; n_lons = 15 n_points = 4

ds = xr.Dataset({'test_var': (['time', 'latitude', 'longitude'], np.random.random((n_times, n_lats, n_lons)))}) ds.to_netcdf('test.nc')

rand_lons = xr.Variable('points', np.random.randint(0, high=n_lons, size=n_points)) rand_lats = xr.Variable('points', np.random.randint(0, high=n_lats, size=n_points))

ds = xr.open_dataset('test.nc', cache=False) points = ds['test_var'][:, rand_lats, rand_lons] yields:

---

NotImplementedError Traceback (most recent call last) <ipython-input-7-f16e4cae9456> in <module>() 12 13 ds = xr.open_dataset('test.nc', cache=False) ---> 14 points = ds['test_var'][:, rand_lats, rand_lons]

~/anaconda/envs/pangeo/lib/python3.6/site-packages/xarray/core/dataarray.py in getitem(self, key) 478 else: 479 # xarray-style array indexing --> 480 return self.isel(**self._item_key_to_dict(key)) 481 482 def setitem(self, key, value):

~/anaconda/envs/pangeo/lib/python3.6/site-packages/xarray/core/dataarray.py in isel(self, drop, indexers) 759 DataArray.sel 760 """ --> 761 ds = self._to_temp_dataset().isel(drop=drop, indexers) 762 return self._from_temp_dataset(ds) 763

~/anaconda/envs/pangeo/lib/python3.6/site-packages/xarray/core/dataset.py in isel(self, drop, indexers) 1390 for name, var in iteritems(self._variables): 1391 var_indexers = {k: v for k, v in indexers_list if k in var.dims} -> 1392 new_var = var.isel(var_indexers) 1393 if not (drop and name in var_indexers): 1394 variables[name] = new_var

~/anaconda/envs/pangeo/lib/python3.6/site-packages/xarray/core/variable.py in isel(self, **indexers) 851 if dim in indexers: 852 key[i] = indexers[dim] --> 853 return self[tuple(key)] 854 855 def squeeze(self, dim=None):

~/anaconda/envs/pangeo/lib/python3.6/site-packages/xarray/core/variable.py in getitem(self, key) 620 """ 621 dims, indexer, new_order = self._broadcast_indexes(key) --> 622 data = as_indexable(self._data)[indexer] 623 if new_order: 624 data = np.moveaxis(data, range(len(new_order)), new_order)

~/anaconda/envs/pangeo/lib/python3.6/site-packages/xarray/core/indexing.py in getitem(self, key) 554 555 def getitem(self, key): --> 556 return type(self)(_wrap_numpy_scalars(self.array[key])) 557 558 def setitem(self, key, value):

~/anaconda/envs/pangeo/lib/python3.6/site-packages/xarray/core/indexing.py in getitem(self, indexer) 521 522 def getitem(self, indexer): --> 523 return type(self)(self.array, self._updated_key(indexer)) 524 525 def setitem(self, key, value):

~/anaconda/envs/pangeo/lib/python3.6/site-packages/xarray/core/indexing.py in _updated_key(self, new_key) 491 'Vectorized indexing for {} is not implemented. Load your ' 492 'data first with .load() or .compute(), or disable caching by ' --> 493 'setting cache=False in open_dataset.'.format(type(self))) 494 495 iter_new_key = iter(expanded_indexer(new_key.tuple, self.ndim))

NotImplementedError: Vectorized indexing for <class 'xarray.core.indexing.LazilyIndexedArray'> is not implemented. Load your data first with .load() or .compute(), or disable caching by setting cache=False in open_dataset. ```

Problem description

Raising a NotImplementedError here is fine but it instructs the user to "disable caching by setting cache=False in open_dataset" which I've already done. So my questions are 1) should we expect this to work and 2) if not

Expected Output

Ideally, we can get the same behavior as:

```python ds = xr.open_dataset('test2.nc', cache=False).load() points = ds['test_var'][:, rand_lats, rand_lons]

<xarray.DataArray 'test_var' (time: 4, points: 4)> array([[0.939469, 0.406885, 0.939469, 0.759075], [0.470116, 0.585546, 0.470116, 0.37833 ], [0.274321, 0.648218, 0.274321, 0.383391], [0.754121, 0.078878, 0.754121, 0.903788]]) Dimensions without coordinates: time, points ```

without needing to use .load()

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.6.4.final.0 python-bits: 64 OS: Linux OS-release: 3.10.0-693.5.2.el7.x86_64 machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8 xarray: 0.10.0+dev55.g1d32399 pandas: 0.22.0 numpy: 1.14.0 scipy: 1.0.0 netCDF4: 1.3.1 h5netcdf: 0.5.0 h5py: 2.7.1 Nio: None zarr: None bottleneck: 1.2.1 cyordereddict: None dask: 0.16.1 distributed: 1.20.2 matplotlib: 2.1.2 cartopy: 0.15.1 seaborn: 0.8.1 setuptools: 38.4.0 pip: 9.0.1 conda: None pytest: 3.4.0 IPython: 6.2.1 sphinx: None