issues: 755105132

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755105132 MDU6SXNzdWU3NTUxMDUxMzI= 4641 Wrong hue assignment in scatter plot 42246615 closed 0     7 2020-12-02T09:34:40Z 2021-01-13T23:02:33Z 2021-01-13T23:02:33Z NONE      

What happened: When using the hue keyword in a scatter plot to color the points based on a string variable, the color assignment in the plot is wrong (whereas the legend is correct).

What you expected to happen: In the example, data of category "A" ranges between 0 and 2 in u-direction and 0 and 0.5 in v-direction. Points in that square should be orange (the color for "A") but currently are blue.

Minimal Complete Verifiable Example:

```python import xarray as xr import numpy as np

u = np.random.rand(50, 2) * np.array([1, 2]) v = np.random.rand(50, 2) * np.array([1, 0.5])

ds = xr.Dataset( { "u": (("x", "category"), u), "v": (("x", "category"), v), }, coords={"category": ["B", "A"],} )

g = ds.plot.scatter( y="u", x="v", hue="category", ); ```

Anything else we need to know?: I think that this might be related to sorting at some point. If the variable by which I color is sorted alphabetically (["A", "B"] instead of ["B", "A"]), the color assignment is correct.

Not sure if this issue is related to https://github.com/pydata/xarray/issues/4126, bit it looks different to me (the problem is not the legend, but the colors in the plot itself).

Environment:

Output of <tt>xr.show_versions()</tt> INSTALLED VERSIONS ------------------ commit: None python: 3.7.8 | packaged by conda-forge | (default, Jul 31 2020, 02:25:08) [GCC 7.5.0] python-bits: 64 OS: Linux OS-release: 4.15.0-122-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8 libhdf5: 1.10.6 libnetcdf: 4.7.4 xarray: 0.16.0 pandas: 1.1.2 numpy: 1.17.5 scipy: 1.5.2 netCDF4: 1.5.4 pydap: None h5netcdf: None h5py: 2.10.0 Nio: None zarr: 2.4.0 cftime: 1.2.1 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: 2.26.0 distributed: 2.26.0 matplotlib: 3.3.2 cartopy: None seaborn: 0.11.0 numbagg: None pint: None setuptools: 49.6.0.post20200814 pip: 20.2.3 conda: 4.8.3 pytest: 6.0.1 IPython: 7.18.1 sphinx: None 
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