Assume longitude is cyclic in _interp_nominal_lon (#296)

* assume longitude is cyclic

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Fix scaffolding

* Update whats-new.rst

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Julius Busecke <julius@ldeo.columbia.edu>

docs/whats-new.rst

@@ -15,6 +15,10 @@ Internal Changes
 - Added 'nvertices' -> 'vertex' to renaming preprocessor (:pull:`357`). By `Julius Busecke <https://github.com/jbusecke>`
 - Updated mamba CI + testing py311/py312 (:issue:`360`, :pull:`362`). By `Julius Busecke <https://github.com/jbusecke>`
 
+Bugfixes
+~~~~~~~~
+- Fixed cyclic interpolation in `_interp_nominal_lon` (:issue:`295`, :pull:`296`). By `Joran Angevaare <https://github.com/JoranAngevaare>`
+
 .. _whats-new.0.7.2:
 
 v0.7.3 (unreleased)

xmip/preprocessing.py

@@ -140,7 +140,8 @@ def broadcast_lonlat(ds, verbose=True):
 def _interp_nominal_lon(lon_1d):
  x = np.arange(len(lon_1d))
  idx = np.isnan(lon_1d)
- return np.interp(x, x[~idx], lon_1d[~idx], period=360)
+ # Assume that longitudes are cyclic (i.e. that the period equals the length of lon)
+ return np.interp(x, x[~idx], lon_1d[~idx], period=len(lon_1d))
 
 
 def replace_x_y_nominal_lat_lon(ds):