MCVE Code Sample

```python

In a notebook with html repr enabled

xr.Dataset({0: (('a','b'), np.random.rand(2,3))})

gives:

---

AttributeError Traceback (most recent call last) /j/office/app/research-python/conda/envs/2019.10/lib/python3.7/site-packages/IPython/core/formatters.py in call(self, obj) 343 method = get_real_method(obj, self.print_method) 344 if method is not None: --> 345 return method() 346 return None 347 else:

~/.local/lib/python3.7/site-packages/xarray/core/dataset.py in repr_html(self) 1632 if OPTIONS["display_style"] == "text": 1633 return f"

{escape(repr(self))}

" -> 1634 return formatting_html.dataset_repr(self) 1635 1636 def info(self, buf=None) -> None:

~/.local/lib/python3.7/site-packages/xarray/core/formatting_html.py in dataset_repr(ds) 268 dim_section(ds), 269 coord_section(ds.coords), --> 270 datavar_section(ds.data_vars), 271 attr_section(ds.attrs), 272 ]

~/.local/lib/python3.7/site-packages/xarray/core/formatting_html.py in _mapping_section(mapping, name, details_func, max_items_collapse, enabled) 165 return collapsible_section( 166 name, --> 167 details=details_func(mapping), 168 n_items=n_items, 169 enabled=enabled,

~/.local/lib/python3.7/site-packages/xarray/core/formatting_html.py in summarize_vars(variables) 131 vars_li = "".join( 132 f"

{summarize_variable(k, v)}

" --> 133 for k, v in variables.items() 134 ) 135

~/.local/lib/python3.7/site-packages/xarray/core/formatting_html.py in <genexpr>(.0) 131 vars_li = "".join( 132 f"

{summarize_variable(k, v)}

" --> 133 for k, v in variables.items() 134 ) 135

~/.local/lib/python3.7/site-packages/xarray/core/formatting_html.py in summarize_variable(name, var, is_index, dtype, preview) 96 cssclass_idx = " class='xr-has-index'" if is_index else "" 97 dims_str = f"({', '.join(escape(dim) for dim in var.dims)})" ---> 98 name = escape(name) 99 dtype = dtype or escape(str(var.dtype)) 100

/j/office/app/research-python/conda/envs/2019.10/lib/python3.7/html/init.py in escape(s, quote) 17 translated. 18 """ ---> 19 s = s.replace("&", "&") # Must be done first! 20 s = s.replace("<", "<") 21 s = s.replace(">", ">")

AttributeError: 'int' object has no attribute 'replace'

<xarray.Dataset> Dimensions: (a: 2, b: 3) Dimensions without coordinates: a, b Data variables: 0 (a, b) float64 0.5327 0.927 0.8582 0.8825 0.9478 0.09475 ```

Problem Description

I think this may be an uncomplicated fix: coerce the keys to str

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.7.3 | packaged by conda-forge | (default, Jul 1 2019, 21:52:21) [GCC 7.3.0] python-bits: 64 OS: Linux OS-release: ... machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.utf8 LOCALE: en_US.UTF-8 libhdf5: 1.10.5 libnetcdf: 4.7.1 xarray: 0.15.0 pandas: 1.0.1 numpy: 1.17.3 scipy: 1.3.2 netCDF4: 1.5.3 pydap: None h5netcdf: 0.7.4 h5py: 2.10.0 Nio: None zarr: None cftime: 1.0.4.2 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: 1.2.1 dask: 2.7.0 distributed: 2.7.0 matplotlib: 3.1.2 cartopy: None seaborn: 0.9.0 numbagg: installed setuptools: 41.6.0.post20191101 pip: 19.3.1 conda: None pytest: 5.2.2 IPython: 7.9.0 sphinx: 2.2.1