1.5: fix Size_Inner_Difference in Delboeuf/Ebbinghaus, repair the README workflow

.github/workflows/readme.yml

@@ -5,26 +5,49 @@ on:
     paths:
       - README.Rmd
 
+# Needed for the commit step to push the re-rendered README back
+permissions:
+  contents: write
+
 jobs:
   render:
     name: Render README
-    runs-on: macOS-latest
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+
       - uses: r-lib/actions/setup-r@v2
+        with:
+          use-public-rspm: true
       - uses: r-lib/actions/setup-pandoc@v2
-      - name: Install Core Dependencies
-        run: Rscript -e 'install.packages(c("rmarkdown", "dplyr", "remotes"))'
-      - name: Install Python
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.x"
+
+      # README.Rmd imports pyllusion itself, so install the package (which brings in numpy, pandas,
+      # Pillow and scipy) rather than a hand-listed subset of its dependencies.
+      - name: Install Python dependencies
         run: |
-            Rscript -e "remotes::install_github('rstudio/reticulate')"
-            Rscript -e "reticulate::install_miniconda()"
-            Rscript -e "reticulate::py_install(c('Pillow', 'scipy'), pip = TRUE)"
+          python -m pip install --upgrade pip
+          python -m pip install .
+
+      # reticulate comes from CRAN. It used to be installed from GitHub via remotes, which failed
+      # because an unauthenticated install_github() falls back to the bundled PAT and gets rate
+      # limited; there is no need for the development version here anyway.
+      - name: Install R dependencies
+        run: Rscript -e 'install.packages(c("rmarkdown", "reticulate"))'
+
       - name: Render README
+        env:
+          # Point reticulate at the interpreter set up above, instead of the local path in README.Rmd
+          RETICULATE_PYTHON: ${{ env.pythonLocation }}/bin/python
         run: Rscript -e 'rmarkdown::render("README.Rmd")'
+
       - name: Commit results
         run: |
           git config --local user.email "41898282+github-actions[bot]@users.noreply.github.com"
           git config --local user.name "github-actions[bot]"
-          git commit README.md -m 'Re-build README.Rmd' || echo "No changes to commit"
-          git push origin || echo "No changes to commit"
+          git add README.md docs/img
+          git commit -m 'Re-build README.Rmd' || echo "No changes to commit"
+          git push origin HEAD:"${GITHUB_REF_NAME}" || echo "Nothing to push"

NEWS.rst

@@ -1,6 +1,27 @@
 News
 =====
 
+1.5
+---------
+
+**Fixes**
+
+- ``Delboeuf`` and ``Ebbinghaus``: fixed ``Size_Inner_Difference`` in ``get_parameters()``. An operator
+  precedence slip (``np.pi * a**2 / np.pi * b**2``, which evaluates as ``(pi * a**2 / pi) * b**2``) made
+  it return the product of the two squared radii instead of a difference of areas - it reported
+  0.000244140625 for two circles of *identical* size. It is now the signed difference between the areas
+  of the two inner circles, positive when the left circle is larger, as its docstring always described.
+  Both illusions were affected, since ``Ebbinghaus`` reuses the same helper. **Any analysis that used
+  this value will need re-running.**
+- Corrected the name of that entry in the ``Delboeuf`` and ``Ebbinghaus`` docstrings, where it was
+  listed as ``Sine_Inner_Difference``.
+
+**Misc**
+
+- Repaired the "Render README" workflow, which could not run: it installed reticulate from GitHub
+  (rate limited without a token), never installed Pyllusion itself although ``README.Rmd`` imports it,
+  and relied on a hard-coded local path to a Python distribution.
+
 1.4
 ---------
 

README.Rmd

@@ -24,11 +24,14 @@ knitr::opts_chunk$set(
 
 
 
-# Setup python - you need to change the path to your python distribution
+# Setup python - locally, point `local_python` at your own python distribution. On CI the
+# interpreter comes from RETICULATE_PYTHON instead, so the local path is skipped there (it also
+# gets skipped if it does not exist, so a wrong path does not break anyone else's render).
 library(reticulate)
-# reticulate::use_python("D:/Downloads/WPy64-3902/python-3.9.0.amd64/")
-reticulate::use_python("C:/Users/Zen Juen/Downloads/WPy64-3850/python-3.8.5.amd64")
-# reticulate::use_python("C:/Users/Pham Thanh Tam/Desktop/WPy-3710b/python-3.7.1.amd64")
+local_python <- "C:/Users/Zen Juen/Downloads/WPy64-3850/python-3.8.5.amd64"
+if (!nzchar(Sys.getenv("CI")) && dir.exists(local_python)) {
+  reticulate::use_python(local_python)
+}
 
 
 # matplotlib <- import("matplotlib")

pyllusion/Delboeuf/Delboeuf.py

@@ -88,7 +88,7 @@ def get_parameters(self):
             - **Illusion_Type** : `Congruent` if the illusion enhances the perception of the objective difference in the illusion, and `Incongruent` if it reduces the perceived  difference.
             - **Size_Inner_Left** : Size of the inner left circle.
             - **Size_Inner_Right** : Size of the inner right circle.
-            - **Sine_Inner_Difference** : Difference in areas of the left and right inner circles.
+            - **Size_Inner_Difference** : Difference in areas of the left and right inner circles (signed, positive when the left circle is larger).
             - **Size_Outer_Left** : Size of the outer left rim.
             - **Size_Outer_Right** : Size of the outer right rim.
             - **Distance** : Distance between the circles, by modifying `distance` of delboeuf_parameters().

pyllusion/Delboeuf/delboeuf_parameters.py

@@ -109,10 +109,17 @@ def _delboeuf_parameters_sizeinner(difference=0, size_min=0.25):
         inner_size_right = size_bigger
         inner_size_left = size_min
 
+    # Signed difference between the areas of the two inner circles, positive when the left one is
+    # larger. Note the parentheses: written as `np.pi * a**2 / np.pi * b**2` this evaluates left to
+    # right as `(pi * a**2 / pi) * b**2`, i.e. the product of the squared radii, which is what this
+    # returned before.
+    area_left = np.pi * (inner_size_left / 2) ** 2
+    area_right = np.pi * (inner_size_right / 2) ** 2
+
     parameters = {
         "Difference": difference,
         "Size_Inner_Left": inner_size_left,
         "Size_Inner_Right": inner_size_right,
-        "Size_Inner_Difference": np.pi * (size_bigger / 2) ** 2 / np.pi * (size_min / 2) ** 2,
+        "Size_Inner_Difference": area_left - area_right,
     }
     return parameters

pyllusion/Ebbinghaus/Ebbinghaus.py

@@ -84,7 +84,7 @@ def get_parameters(self):
             - **Illusion_Type** : `Congruent` if the illusion enhances the perception of the objective difference in the illusion, and `Incongruent` if it reduces the perceived difference.
             - **Size_Inner_Left** : Size of the inner left circle.
             - **Size_Inner_Right** : Size of the inner right circle.
-            - **Sine_Inner_Difference** : Difference in areas of the left and right inner circles.
+            - **Size_Inner_Difference** : Difference in areas of the left and right inner circles (signed, positive when the left circle is larger).
             - **Size_Outer_Left** : Size of the surrounding circles around the left inner circle.
             - **Size_Outer_Right** : Size of the surrounding circles around the right inner circle.
             - **Distance**: Distance between the circles, by modifying `distance` of ebbinghaus_parameters().

pyllusion/__init__.py

@@ -1,7 +1,7 @@
 """
 The Pyllusion module.
 """
-__version__ = "1.4"
+__version__ = "1.5"
 
 from .Autostereogram import *
 

tests/__init__.py

@@ -1,4 +1,6 @@
 import numpy as np
+import pytest
+
 import pyllusion
 
 
@@ -498,3 +500,26 @@ def test_analyze_luminance():
 
     out = pyllusion.analyze_luminance(image, average=False)
     assert out["Luminance"].shape == (50, 50)
+
+
+def test_size_inner_difference():
+    # `Size_Inner_Difference` is the signed difference between the areas of the two inner circles.
+    # It used to be mis-parenthesised (`pi * a**2 / pi * b**2`, which is the product of the squared
+    # radii) and returned 0.000244140625 for two circles of identical size.
+    for illusion in [pyllusion.Delboeuf, pyllusion.Ebbinghaus]:
+        # Identical circles -> no difference
+        parameters = illusion(difference=0).get_parameters()
+        assert parameters["Size_Inner_Difference"] == 0
+
+        # Positive difference -> left circle larger -> positive area difference
+        parameters = illusion(difference=1).get_parameters()
+        area_left = np.pi * (parameters["Size_Inner_Left"] / 2) ** 2
+        area_right = np.pi * (parameters["Size_Inner_Right"] / 2) ** 2
+        assert parameters["Size_Inner_Difference"] == pytest.approx(area_left - area_right)
+        assert parameters["Size_Inner_Difference"] > 0
+        # difference=1 doubles the area, as the size is scaled by sqrt(1 + abs(difference))
+        assert area_left == pytest.approx(2 * area_right)
+
+        # Sign follows the side the larger circle is on
+        parameters = illusion(difference=-1).get_parameters()
+        assert parameters["Size_Inner_Difference"] < 0