[BUG] replace combine with itertools product

.github/workflows/ci.yml

@@ -66,8 +66,6 @@ jobs:
     steps:
     - uses: actions/checkout@v4
 
-    - uses: codecov/codecov-action@v3
-
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v5
       with:
@@ -84,3 +82,5 @@ jobs:
     - name: Test with pytest
       run: |
         pytest --cov=pygam
+
+    - uses: codecov/codecov-action@v3

pygam/pygam.py

@@ -1,6 +1,7 @@
 import warnings
 from collections import OrderedDict, defaultdict
 from copy import deepcopy
+from itertools import product
 
 import numpy as np
 import scipy as sp
@@ -74,7 +75,6 @@
     check_X_y,
     check_y,
     cholesky,
-    combine,
     flatten,
     isiterable,
     load_diagonal,
@@ -1969,6 +1969,8 @@ def gridsearch(
         admissible_params = list(self.get_params()) + self._plural
         params = []
         grids = []
+
+        grid_size = 1
         for param, grid in list(param_grids.items()):
             # check param exists
             if param not in (admissible_params):
@@ -2001,20 +2003,21 @@ def gridsearch(
                 if cartesian:
                     if len(grid) != target_len:
                         raise ValueError(msg)
-                    grid = combine(*grid)
 
-                if not all([len(subgrid) == target_len for subgrid in grid]):
-                    raise ValueError(msg)
+                    # we should consider each element in `grid` its own dimension
+                    grid_size *= np.prod([len(g) for g in grid])
+                    grid = product(*grid)
+                else:
+                    if not all([len(subgrid) == target_len for subgrid in grid]):
+                        raise ValueError(msg)
+                    grid_size *= len(grid)
+            else:
+                grid_size *= len(grid)
 
             # save param name and grid
             params.append(param)
             grids.append(grid)
 
-        # build a list of dicts of candidate model params
-        param_grid_list = []
-        for candidate in combine(*grids):
-            param_grid_list.append(dict(zip(params, candidate)))
-
         # set up data collection
         best_model = None  # keep the best model
         best_score = np.inf
@@ -2039,7 +2042,10 @@ def pbar(x):
                 return x
 
         # loop through candidate model params
-        for param_grid in pbar(param_grid_list):
+        for grid in pbar(product(*grids), max_value=grid_size):
+            # build dict of candidate model params
+            param_grid = dict(zip(params, grid))
+
             try:
                 # try fitting
                 # define new model

pygam/utils.py

@@ -787,33 +787,6 @@ def ylogydu(y, u):
     return out
 
 
-def combine(*args):
-    """
-    Tool to perform tree search via recursion
-    useful for developing the grid in a grid search.
-
-    Parameters
-    ----------
-    args : list of lists
-
-    Returns
-    -------
-    list of all the combinations of the elements in the input lists
-    """
-    if hasattr(args, "__iter__") and (len(args) > 1):
-        subtree = combine(*args[:-1])
-        tree = []
-        for leaf in subtree:
-            for node in args[-1]:
-                if hasattr(leaf, "__iter__"):
-                    tree.append(leaf + [node])
-                else:
-                    tree.append([leaf] + [node])
-        return tree
-    else:
-        return [[arg] for arg in args[0]]
-
-
 def isiterable(obj, reject_string=True):
     """Convenience tool to detect if something is iterable.
     in python3, strings count as iterables to we have the option to exclude them.