Description
What happened?
I was trying to use polyval with a cftime coordinate and it failed with TypeError: unsupported operand type(s) for *: 'float' and 'cftime._cftime.DatetimeNoLeap'. The error seems to originate from #6548, where the process transforming coordinates to numerical values was modified. The new _ensure_numeric method seems to ignore the possibility of cftime arrays.
What did you expect to happen?
A polynomial to be evaluated along my coordinate.
Minimal Complete Verifiable Example
import xarray as xr
import numpy as np
# use_cftime=False will work
t = xr.date_range('2001-01-01', periods=100, use_cftime=True, freq='YS')
da = xr.DataArray(np.arange(100) ** 3, dims=('time',), coords={'time': t})
coeffs = da.polyfit('time', 4)
da2 = xr.polyval(da.time, coeffs).polyfit_coefficientsMVCE 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.
Relevant log output
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
Input In [5], in <cell line: 4>()
2 da = xr.DataArray(np.arange(100) ** 3, dims=('time',), coords={'time': t})
3 coeffs = da.polyfit('time', 4)
----> 4 da2 = xr.polyval(da.time, coeffs).polyfit_coefficients
File ~/Python/xarray/xarray/core/computation.py:1931, in polyval(coord, coeffs, degree_dim)
1929 res = zeros_like(coord) + coeffs.isel({degree_dim: max_deg}, drop=True)
1930 for deg in range(max_deg - 1, -1, -1):
-> 1931 res *= coord
1932 res += coeffs.isel({degree_dim: deg}, drop=True)
1934 return res
File ~/Python/xarray/xarray/core/_typed_ops.py:103, in DatasetOpsMixin.__imul__(self, other)
102 def __imul__(self, other):
--> 103 return self._inplace_binary_op(other, operator.imul)
File ~/Python/xarray/xarray/core/dataset.py:6107, in Dataset._inplace_binary_op(self, other, f)
6105 other = other.reindex_like(self, copy=False)
6106 g = ops.inplace_to_noninplace_op(f)
-> 6107 ds = self._calculate_binary_op(g, other, inplace=True)
6108 self._replace_with_new_dims(
6109 ds._variables,
6110 ds._coord_names,
(...)
6113 inplace=True,
6114 )
6115 return self
File ~/Python/xarray/xarray/core/dataset.py:6154, in Dataset._calculate_binary_op(self, f, other, join, inplace)
6152 else:
6153 other_variable = getattr(other, "variable", other)
-> 6154 new_vars = {k: f(self.variables[k], other_variable) for k in self.data_vars}
6155 ds._variables.update(new_vars)
6156 ds._dims = calculate_dimensions(ds._variables)
File ~/Python/xarray/xarray/core/dataset.py:6154, in <dictcomp>(.0)
6152 else:
6153 other_variable = getattr(other, "variable", other)
-> 6154 new_vars = {k: f(self.variables[k], other_variable) for k in self.data_vars}
6155 ds._variables.update(new_vars)
6156 ds._dims = calculate_dimensions(ds._variables)
File ~/Python/xarray/xarray/core/_typed_ops.py:402, in VariableOpsMixin.__mul__(self, other)
401 def __mul__(self, other):
--> 402 return self._binary_op(other, operator.mul)
File ~/Python/xarray/xarray/core/variable.py:2494, in Variable._binary_op(self, other, f, reflexive)
2491 attrs = self._attrs if keep_attrs else None
2492 with np.errstate(all="ignore"):
2493 new_data = (
-> 2494 f(self_data, other_data) if not reflexive else f(other_data, self_data)
2495 )
2496 result = Variable(dims, new_data, attrs=attrs)
2497 return result
TypeError: unsupported operand type(s) for *: 'float' and 'cftime._cftime.DatetimeGregorian'Anything else we need to know?
I also noticed that since the Horner PR, polyfit and polyval do not use the same function to convert coordinates into numerical values. Isn't this dangerous?
Environment
INSTALLED VERSIONS
commit: None
python: 3.10.4 | packaged by conda-forge | (main, Mar 24 2022, 17:38:57) [GCC 10.3.0]
python-bits: 64
OS: Linux
OS-release: 3.10.0-1160.49.1.el7.x86_64
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_CA.UTF-8
LOCALE: ('en_CA', 'UTF-8')
libhdf5: 1.12.1
libnetcdf: 4.8.1
xarray: 2022.3.1.dev267+gd711d58
pandas: 1.4.2
numpy: 1.21.6
scipy: 1.8.0
netCDF4: 1.5.8
pydap: None
h5netcdf: None
h5py: 3.6.0
Nio: None
zarr: 2.11.3
cftime: 1.6.0
nc_time_axis: 1.4.1
PseudoNetCDF: None
rasterio: None
cfgrib: None
iris: None
bottleneck: 1.3.4
dask: 2022.04.1
distributed: 2022.4.1
matplotlib: 3.5.1
cartopy: 0.20.2
seaborn: None
numbagg: None
fsspec: 2022.3.0
cupy: None
pint: 0.19.2
sparse: 0.13.0
flox: 0.5.0
numpy_groupies: 0.9.15
setuptools: 62.1.0
pip: 22.0.4
conda: None
pytest: None
IPython: 8.2.0
sphinx: 4.5.0