issues

```python import pandas as pd import xarray as xr

df = pd.DataFrame(data=[0, 1], index=list("aa")) da = xr.DataArray(df) print(df.loc[list("a")]) # works print(da.loc[{"dim_0": list("a")}]) # fails ``` Xarray fails with the exception

Traceback (most recent call last): File "session4.py", line 7, in <module> print(da.loc[{"dim_0": list("a")}]) # fails File "/usr/local/anaconda3/lib/python3.6/site-packages/xarray/core/dataarray.py", line 104, in __getitem__ return self.data_array.sel(**key) File "/usr/local/anaconda3/lib/python3.6/site-packages/xarray/core/dataarray.py", line 784, in sel indexers=indexers, drop=drop, method=method, tolerance=tolerance) File "/usr/local/anaconda3/lib/python3.6/site-packages/xarray/core/dataset.py", line 1509, in sel self, indexers=indexers, method=method, tolerance=tolerance) File "/usr/local/anaconda3/lib/python3.6/site-packages/xarray/core/coordinates.py", line 355, in remap_label_indexers obj, v_indexers, method=method, tolerance=tolerance File "/usr/local/anaconda3/lib/python3.6/site-packages/xarray/core/indexing.py", line 250, in remap_label_indexers dim, method, tolerance) File "/usr/local/anaconda3/lib/python3.6/site-packages/xarray/core/indexing.py", line 186, in convert_label_indexer indexer = get_indexer_nd(index, label, method, tolerance) File "/usr/local/anaconda3/lib/python3.6/site-packages/xarray/core/indexing.py", line 117, in get_indexer_nd flat_indexer = index.get_indexer(flat_labels, **kwargs) File "/usr/local/anaconda3/lib/python3.6/site-packages/pandas/core/indexes/base.py", line 3244, in get_indexer raise InvalidIndexError('Reindexing only valid with uniquely' pandas.core.indexes.base.InvalidIndexError: Reindexing only valid with uniquely valued Index objects

Output of xr.show_versions()

``` INSTALLED VERSIONS

commit: None python: 3.6.6.final.0 python-bits: 64 OS: Darwin OS-release: 17.7.0 machine: x86_64 processor: i386 byteorder: little LC_ALL: None LANG: en_GB.UTF-8 LOCALE: en_GB.UTF-8

xarray: 0.10.8 pandas: 0.23.4 numpy: 1.15.1 scipy: 1.1.0 netCDF4: 1.4.1 h5netcdf: None h5py: 2.8.0 Nio: None zarr: None bottleneck: 1.2.1 cyordereddict: None dask: 0.19.0 distributed: 1.23.0 matplotlib: 2.2.3 cartopy: None seaborn: 0.9.0 setuptools: 40.2.0 pip: 18.0 conda: 4.5.11 pytest: 3.7.3 IPython: 6.5.0 sphinx: 1.7.7 ```

There is a KeyError at xarray.backends.file_manager.CachingFileManager for the acquire method on these lines:

with self._lock: try: file = self._cache[self._key]

which does not happen when I test on my macos.

Let me know if you require further testing on my part.

Full log:

``` =================================== FAILURES ===================================

_____ testqtl_xarr _______

self = <xarray.backends.file_manager.CachingFileManager object at 0x7f59e2cab978>

def acquire(self):

    """Acquiring a file object from the manager.



    A new file is only opened if it has expired from the

    least-recently-used cache.



    This method uses a reentrant lock, which ensures that it is

    thread-safe. You can safely acquire a file in multiple threads at the

    same time, as long as the underlying file object is thread-safe.



    Returns

    -------

    An open file object, as returned by ``opener(*args, **kwargs)``.

    """

    with self._lock:

        try:

          file = self._cache[self._key]

miniconda/envs/test-environment/lib/python3.6/site-packages/xarray/backends/file_manager.py:137:

self = <xarray.backends.lru_cache.LRUCache object at 0x7f5a04a9c630>

key = [<function _open_netcdf4_group at 0x7f5a04abc1e0>, ('/tmp/tmprj8lwlat/xarr.hdf5', CombinedLock([<SerializableLock: 447...>])), 'r', (('clobber', True), ('diskless', False), ('format', 'NETCDF4'), ('group', '/foo/chr1'), ('persist', False))]

def __getitem__(self, key):

    # record recent use of the key by moving it to the front of the list

    with self._lock:

      value = self._cache[key]

E KeyError: [<function _open_netcdf4_group at 0x7f5a04abc1e0>, ('/tmp/tmprj8lwlat/xarr.hdf5', CombinedLock([<SerializableLock: 4471090f-419e-49bd-9d27-4156e09febdd>, <SerializableLock: b9eb5ba1-2830-402e-b48f-3ef45768b7c2>])), 'r', (('clobber', True), ('diskless', False), ('format', 'NETCDF4'), ('group', '/foo/chr1'), ('persist', False))]

miniconda/envs/test-environment/lib/python3.6/site-packages/xarray/backends/lru_cache.py:43: KeyError

During handling of the above exception, another exception occurred:

def test_qtl_xarr():

    with limix.example.file_example("xarr.hdf5.bz2") as filepath:

        filepath = limix.sh.extract(filepath, verbose=False)

        sample_ids = limix.io.hdf5.fetch(filepath, "/foo/chr1/col_header/sample_ids")



        rsid = dict()

        for i in range(1, 3):

            rsid[i] = limix.io.hdf5.fetch(

                filepath, "/foo/chr{}/row_header/rsid".format(i)

            )



        G = []

        for i in range(1, 3):

          g = xr.open_dataset(filepath, "/foo/chr{}".format(i))["matrix"]

miniconda/envs/test-environment/lib/python3.6/site-packages/limix/qtl/test/test_qtl_xarr.py:20:

miniconda/envs/test-environment/lib/python3.6/site-packages/xarray/backends/api.py:320: in open_dataset

filename_or_obj, group=group, lock=lock, **backend_kwargs)

miniconda/envs/test-environment/lib/python3.6/site-packages/xarray/backends/netCDF4_.py:355: in open

return cls(manager, lock=lock, autoclose=autoclose)

miniconda/envs/test-environment/lib/python3.6/site-packages/xarray/backends/netCDF4_.py:314: in init

self.format = self.ds.data_model

miniconda/envs/test-environment/lib/python3.6/site-packages/xarray/backends/netCDF4_.py:359: in ds

return self._manager.acquire().value

miniconda/envs/test-environment/lib/python3.6/site-packages/xarray/backends/file_manager.py:143: in acquire

file = self._opener(*self._args, **kwargs)

miniconda/envs/test-environment/lib/python3.6/site-packages/xarray/backends/netCDF4_.py:247: in _open_netcdf4_group

ds = nc4.Dataset(filename, mode=mode, **kwargs)

netCDF4/_netCDF4.pyx:2135: in netCDF4._netCDF4.Dataset.init

???

???

E OSError: [Errno -101] NetCDF: HDF error: b'/tmp/tmprj8lwlat/xarr.hdf5'

netCDF4/_netCDF4.pyx:1752: OSError

===================== 1 failed, 50 passed in 65.82 seconds =====================

The command "bash <(curl -fsSL https://raw.githubusercontent.com/horta/ci/master/travis.sh)" exited with 1.

Done. Your build exited with 1. ```

You don't need to have pytest-runner before-hand.