interpolate using quadratic returns nan

[nkarasiak]

What happened?

When using a multiple dimensions xarray (like time, x and y), the quadratic function is not working anymore with interpolate, it returns only nan. slinear is ok. quadratic is only ok when using only a dimension (like only a lat/lon value).

What did you expect to happen?

No response

Minimal Complete Verifiable Example

import xarray as xr

ds = xr.tutorial.load_dataset("ersstv5")
# Generate a subset
subset = ds['sst'].isel(time=slice(0,10),lat=slice(20,40),lon=slice(20,40))
## Plot images
subset.plot(col="time",col_wrap=6)

# Interpolate with quadratic
subset_quadratic = subset.resample(time='10D').interpolate('quadratic')
## subset_quadratic is now full of NaN
subset_quadratic.plot(col="time",col_wrap=6)

# Working with only time dimension
subset_quadratic = subset.isel(lat=0,lon=0).resample(time='10D').interpolate('quadratic')
subset_quadratic.plot()

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.
• Recent environment — the issue occurs with the latest version of xarray and its dependencies.

Relevant log output

No response

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS ------------------ commit: None python: 3.12.3 | packaged by conda-forge | (main, Apr 15 2024, 18:20:11) [MSC v.1938 64 bit (AMD64)] python-bits: 64 OS: Windows OS-release: 11 machine: AMD64 processor: Intel64 Family 6 Model 186 Stepping 3, GenuineIntel byteorder: little LC_ALL: None LANG: en LOCALE: ('fr_FR', 'cp1252') libhdf5: 1.14.3 libnetcdf: None

xarray: 2024.5.0
pandas: 2.1.4
numpy: 1.26.4
scipy: 1.13.0
netCDF4: None
pydap: None
h5netcdf: 1.3.0
h5py: 3.11.0
zarr: 2.18.0
cftime: None
nc_time_axis: None
iris: None
bottleneck: None
dask: 2024.5.0
distributed: 2024.5.0
matplotlib: 3.8.4
cartopy: None
seaborn: 0.13.2
numbagg: None
fsspec: 2024.3.1
cupy: None
pint: None
sparse: None
flox: None
numpy_groupies: None
setuptools: 69.5.1
pip: 24.0
conda: None
pytest: None
mypy: None
IPython: 8.24.0
sphinx: 7.3.7

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