add a functools.cache decorator to predictions / central predictions, as

the higher-level functions that are (usually called) by chi2/plotting/t0
functions

Author: scarlehoff

validphys2/src/validphys/convolution.py

@@ -43,8 +43,8 @@
 import numpy as np
 import pandas as pd
 
-from validphys.pdfbases import evolution
 import validphys
+from validphys.pdfbases import evolution
 
 FK_FLAVOURS = evolution.to_known_elements(
     [
@@ -176,6 +176,7 @@ def _predictions(dataset, pdf, fkfunc):
     return opfunc(*all_predictions)
 
 
+@functools.cache
 def predictions(dataset, pdf):
     """ "Compute theory predictions for a given PDF and dataset. Information
     regading the dataset, on cuts, CFactors and combinations of FKTables is
@@ -227,6 +228,7 @@ def predictions(dataset, pdf):
     return _predictions(dataset, pdf, fk_predictions)
 
 
+@functools.cache
 def central_predictions(
     dataset: validphys.core.DataSetSpec, pdf: validphys.core.PDF
 ) -> pd.DataFrame: