Inconsistent xarray dimensions use between holoviews and geoviews

The same data is being plotted differently into an Image using either holoviews or geoviews. Is this related to how geoviews uses boundaries, a mention I find in just one line of the docs of geoviews when comparing to the Iris library?

Here’s how I create the datasets:

kdims = ['simtime', 'lyr_mid', ('lon', 'Longitude'), ('lat','Latitude')]
vdims = ['wind_mag', 'wind_dir']
xr_dataset = gv.Dataset(xr_ensemble, kdims=kdims, vdims=vdims, crs=crs.PlateCarree())
hv_dataset = hv.Dataset(xr_ensemble, kdims=kdims, vdims=vdims)

Here’s the geoviews Image plot:

%%opts Image [aspect=1.5]
xr_dataset.select(simtime=(24096,24098)).to(gv.Image, ['lon', 'lat'], 'wind_mag')

and here the holoviews Image plot:

%%opts Image [aspect=1.5]
hv_dataset.select(simtime=(24096,24098)).to(hv.Image, ['lon', 'lat'], 'wind_mag')

As you can see the latitude has 4 bins, and all bins are shown in the holoviews Image plot, but the geoviews Image plot is using the value of the first latitude dimension, 70, as a boundary instead of centering the bin around that number, which is how this netCDF data was compiled.

How can I make geoviews treat the data the same way holoviews already does?

Here’s the .coords view of the xarray object:

Coordinates:
  * lyr_mid  (lyr_mid) float64 0.992 0.9975 0.9995
  * lon      (lon) float64 -180.0 -174.0 -168.0 -162.0 -156.0 -150.0 -144.0 ...
  * lat      (lat) float64 -85.0 -80.0 -75.0 -70.0
  * simtime  (simtime) float64 2.41e+04 2.41e+04 2.41e+04 2.41e+04 2.41e+04 ...

My system data:

• macOS 10.12.5
• python 3.6 using conda-forge, all current versions
• geoviews via the ioam channel
• Chrome Browser Version 59.0.3071.115 (Official Build) (64-bit)

[philippjfr]

The fix was merged in the referenced PR, closing.

[lukasbindreiter]

Any updates on this?

This definetly looks like an issue in boundary calculation. If you look at the latitude axis, it ranges from -70 to -85 in geoviews and from -65 to -90 in holoviews.

X Array has images in their documentation which nicely illustrate the difference: Images taken from here

Without bounds calculation

With bounds calculation

In X-Array you can change this behaviour by specifying the infer_intervals argument, which uses this underlying function: _infer_interval_breaks