fix sum problem in fixed effect elements

brainstat/context/genetics.py

@@ -97,7 +97,7 @@ def surface_genetic_expression(
                 with tempfile.NamedTemporaryFile(suffix=".gii", delete=False) as f:
                     name = f.name
                     write_surface(surface, name, otype="gii")
-                surfaces_gii.append(nib.load(name))
+                    surfaces_gii.append(nib.load(name))
             finally:
                 Path(name).unlink()
         else:

brainstat/stats/terms.py

@@ -365,9 +365,14 @@ def __add__(
         return self._add(t)
 
     def __radd__(
-        self, t: Union[ArrayLike, "FixedEffect", "MixedEffect"]
+        self, t: Union[int, ArrayLike, "FixedEffect", "MixedEffect"]
     ) -> "FixedEffect":
-        return self._add(t, side="right")
+        if isinstance(t, int) and t == 0:
+            # When t is 0, return self without adding an extra intercept
+            return self
+        else:
+            # For other cases, proceed with the addition
+            return self._add(t, side="right")
 
     def __sub__(self, t: Union[ArrayLike, "FixedEffect"]) -> "FixedEffect":
         if self.empty:

brainstat/tests/test_genetics.py

@@ -0,0 +1,20 @@
+from brainstat.context.genetics import surface_genetic_expression
+from brainstat.datasets import fetch_parcellation, fetch_template_surface, fetch_parcellation
+import numpy as np
+from nilearn import datasets
+
+# Get Schaefer-100 genetic expression.
+# def test_surface_genetic_expression():
+#     schaefer_100_fs5 = fetch_parcellation("fsaverage5", "schaefer", 100)
+#     surfaces = fetch_template_surface("fsaverage5", join=False)
+#     expression = surface_genetic_expression(schaefer_100_fs5, surfaces, space="fsaverage")
+#     assert expression is not None
+
+
+# def test_surface_genetic_expression2():
+#     destrieux = datasets.fetch_atlas_surf_destrieux()
+#     labels = np.hstack((destrieux['map_left'], destrieux['map_right']))
+#     fsaverage = datasets.fetch_surf_fsaverage()
+#     surfaces = (fsaverage['pial_left'], fsaverage['pial_right'])
+#     expression = surface_genetic_expression(labels, surfaces, space='fsaverage')
+#     assert expression is not None

brainstat/tests/test_terms.py

@@ -2,7 +2,8 @@
 
 import numpy as np
 import pandas as pd
-
+from functools import reduce
+from brainstat.tutorial.utils import fetch_mics_data
 from brainstat.stats.terms import FixedEffect, MixedEffect
 
 
@@ -144,3 +145,11 @@ def test_identity_detection():
 def as_variance(M):
     var = [np.reshape(x[:, None] @ x[None, :], (-1, 1)) for x in M.T]
     return np.squeeze(var, axis=2).T
+
+
+def test_sum():
+    _, demographics = fetch_mics_data()
+    model = []
+    term_age = FixedEffect(demographics.AGE_AT_SCAN)
+    model.append(term_age)
+    assert reduce(lambda x, y: x + y, model) == sum(model)