Using Xarray and Flox for custom non-aggregation functions about flox

[mathause]

I think you may not need groupby for this. And you may also be able to avoid the stacking/ unstacking which can be slow. Can you write a numpy function which does it for one grid point (e.g. using np.interp)? If so you can use xr.apply_ufunc to generalize it to the whole grid. (xr.apply_ufunc can be difficult to grasp sometimes, check out the examples and tutorials, e.g.: https://docs.xarray.dev/en/latest/examples/apply_ufunc_vectorize_1d.html)

• You may also want to check https://docs.xarray.dev/en/latest/user-guide/interpolation.html (but I don't know if it offers what you need)
• I assume you have different pressure at every grid point?

[mgorfer]

Thank you for your answer @mathause (and nice to hear from you again!)

I have explained my problem in more detail in the Xarray discussions
pydata/xarray#8149 (comment)

Because I every grid point has different altitudes at the pressure levels (which I calculate from the geopotential in the original data), my initial thought was that it needs to be done for every grid point separately.

I am doing this with the ERA5 hourly data on pressure levels from 1940 to present. Maybe there is even a dataset in altitude resolution out there, but I wanted to try the pressure to altitude mapping anyway.

[mathause]

nice to hear from you again!

Likewise! I added an xr.apply_ufunc example in pydata/xarray#8149.