ENH: template indicators with jinja

setup.py

@@ -47,6 +47,7 @@
  "scipy>=1.2",
  "statsmodels",
  "xarray>=0.17",
+ "Jinja2",
 ]
 
 dev_requirements = []

xclim/core/formatting.py

@@ -14,8 +14,10 @@
 from inspect import _empty, signature # noqa
 from typing import Any, Mapping, Sequence
 
+import numpy as np
 import xarray as xr
 from boltons.funcutils import wraps
+from jinja2 import Environment
 
 from xclim.core.utils import InputKind, PercentileDataArray
 
@@ -34,6 +36,8 @@
  "pr_per_period": "{unkown}",
 }
 
+jinja_env = Environment(autoescape=True)
+
 
 class AttrFormatter(string.Formatter):
  """A formatter for frequently used attribute values.
@@ -77,7 +81,9 @@ def format(self, format_string: str, /, *args: Any, **kwargs: dict) -> str:
  for k, v in DEFAULT_FORMAT_PARAMS.items():
  if k not in kwargs:
  kwargs.update({k: v})
- return super().format(format_string, *args, **kwargs)
+ kwargs.update({"np": np}) # noqa
+ intermediary_res = jinja_env.from_string(format_string, globals=kwargs).render()
+ return super().format(intermediary_res, *args, **kwargs)
 
  def format_field(self, value, format_spec):
  """Format a value given a formatting spec.

xclim/indicators/atmos/_temperature.py

@@ -172,7 +172,11 @@ class TempWithIndexing(ResamplingIndicatorWithIndexing):
  description="{freq} number of heat wave events over a given period. "
  "An event occurs when the minimum and maximum daily "
  "temperature both exceeds specific thresholds : "
+ "{% if np.isscalar(thresh_tasmin) and np.isscalar(thresh_tasmax)%}"
  "(Tmin > {thresh_tasmin} and Tmax > {thresh_tasmax}) "
+ "{% else %}"
+ "(Tmin > per_gridcell_tmin_thresholds and Tmax > per_gridcell_tmax_thresholds) "
+ "{% endif %}"
  "over a minimum number of days ({window}).",
  cell_methods="",
  keywords="health,",