Added a reverse option to overplot_* (#156)

* Added a reverse option to overplot_*

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Added tests for new overplotting functions (+fixed a bug)

* Extended images for test

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* More reverse options

* Added reverse truths and a test for them

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Bugfix

* bugfix

* fixing baseline images

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Dan F-M <foreman.mackey@gmail.com>

src/corner/arviz_corner.py

@@ -175,6 +175,11 @@ def arviz_corner(
             diverging_mask = np.squeeze(diverging_mask)
             if divergences_kwargs is None:
                 divergences_kwargs = {"color": "C1", "ms": 1}
-            overplot_points(fig, samples[diverging_mask], **divergences_kwargs)
+            overplot_points(
+                fig,
+                samples[diverging_mask],
+                reverse=reverse,
+                **divergences_kwargs,
+            )
 
     return fig

src/corner/core.py

@@ -374,10 +374,11 @@ def corner_impl(
                 )
 
     if truths is not None:
-        overplot_lines(fig, truths, color=truth_color)
+        overplot_lines(fig, truths, reverse=reverse, color=truth_color)
         overplot_points(
             fig,
             [[np.nan if t is None else t for t in truths]],
+            reverse=reverse,
             marker="s",
             color=truth_color,
         )
@@ -683,7 +684,7 @@ def hist2d(
     _set_ylim(new_fig, ax, range[1])
 
 
-def overplot_lines(fig, xs, **kwargs):
+def overplot_lines(fig, xs, reverse=False, **kwargs):
     """
     Overplot lines on a figure generated by ``corner.corner``
 
@@ -698,24 +699,39 @@ def overplot_lines(fig, xs, **kwargs):
        call that originally generated the figure. The entries can optionally
        be ``None`` to omit the line in that axis.
 
+    reverse: bool
+       A boolean flag that should be set to 'True' if the corner plot itself
+       was plotted with 'reverse=True'.
+
     **kwargs
         Any remaining keyword arguments are passed to the ``ax.axvline``
         method.
 
     """
     K = len(xs)
     axes = _get_fig_axes(fig, K)
-    for k1 in range(K):
-        if xs[k1] is not None:
-            axes[k1, k1].axvline(xs[k1], **kwargs)
-        for k2 in range(k1 + 1, K):
+    if reverse:
+        for k1 in range(K):
+            if xs[k1] is not None:
+                axes[K - k1 - 1, K - k1 - 1].axvline(xs[k1], **kwargs)
+            for k2 in range(k1 + 1, K):
+                if xs[k1] is not None:
+                    axes[K - k2 - 1, K - k1 - 1].axvline(xs[k1], **kwargs)
+                if xs[k2] is not None:
+                    axes[K - k2 - 1, K - k1 - 1].axhline(xs[k2], **kwargs)
+
+    else:
+        for k1 in range(K):
             if xs[k1] is not None:
-                axes[k2, k1].axvline(xs[k1], **kwargs)
-            if xs[k2] is not None:
-                axes[k2, k1].axhline(xs[k2], **kwargs)
+                axes[k1, k1].axvline(xs[k1], **kwargs)
+            for k2 in range(k1 + 1, K):
+                if xs[k1] is not None:
+                    axes[k2, k1].axvline(xs[k1], **kwargs)
+                if xs[k2] is not None:
+                    axes[k2, k1].axhline(xs[k2], **kwargs)
 
 
-def overplot_points(fig, xs, **kwargs):
+def overplot_points(fig, xs, reverse=False, **kwargs):
     """
     Overplot points on a figure generated by ``corner.corner``
 
@@ -729,6 +745,10 @@ def overplot_points(fig, xs, **kwargs):
        that is compatible with the :func:`corner.corner` call that originally
        generated the figure.
 
+    reverse: bool
+       A boolean flag that should be set to 'True' if the corner plot itself
+       was plotted with 'reverse=True'.
+
     **kwargs
         Any remaining keyword arguments are passed to the ``ax.plot``
         method.
@@ -739,9 +759,15 @@ def overplot_points(fig, xs, **kwargs):
     xs = _parse_input(xs)
     K = len(xs)
     axes = _get_fig_axes(fig, K)
-    for k1 in range(K):
-        for k2 in range(k1 + 1, K):
-            axes[k2, k1].plot(xs[k1], xs[k2], **kwargs)
+    if reverse:
+        for k1 in range(K):
+            for k2 in range(k1):
+                axes[K - k1 - 1, K - k2 - 1].plot(xs[k2], xs[k1], **kwargs)
+
+    else:
+        for k1 in range(K):
+            for k2 in range(k1 + 1, K):
+                axes[k2, k1].plot(xs[k1], xs[k2], **kwargs)
 
 
 def _parse_input(xs):

tests/test_corner.py

@@ -157,6 +157,13 @@ def test_truths():
     _run_corner(truths=[0.0, None, 0.15])
 
 
+@image_comparison(
+    baseline_images=["reverse_truths"], remove_text=True, extensions=["png"]
+)
+def test_reverse_truths():
+    _run_corner(truths=[0.0, None, 0.15], reverse=True)
+
+
 @image_comparison(
     baseline_images=["no_fill_contours"], remove_text=True, extensions=["png"]
 )
@@ -179,6 +186,82 @@ def test_reverse():
     _run_corner(ndim=2, range=[(4, -4), (-5, 5)])
 
 
+@image_comparison(
+    baseline_images=["extended_overplotting"],
+    remove_text=True,
+    extensions=["png"],
+)
+def test_extended_overplotting():
+    # Test overplotting a more complex plot
+    labels = [r"$\theta_1$", r"$\theta_2$", r"$\theta_3$", r"$\theta_4$"]
+
+    figure = _run_corner(ndim=4, reverse=False, labels=labels)
+
+    # Set same results:
+    ndim, nsamples = 4, 10000
+    np.random.seed(1234)
+
+    data1 = np.random.randn(ndim * 4 * nsamples // 5).reshape(
+        [4 * nsamples // 5, ndim]
+    )
+    mean = 4 * np.random.rand(ndim)
+    data2 = mean[None, :] + np.random.randn(ndim * nsamples // 5).reshape(
+        [nsamples // 5, ndim]
+    )
+    samples = np.vstack([data1, data2])
+
+    value1 = mean
+    # This is the empirical mean of the sample:
+    value2 = np.mean(data1, axis=0)
+
+    corner.overplot_lines(figure, value1, color="C1", reverse=False)
+    corner.overplot_points(
+        figure, value1[None], marker="s", color="C1", reverse=False
+    )
+    corner.overplot_lines(figure, value2, color="C2", reverse=False)
+    corner.overplot_points(
+        figure, value2[None], marker="s", color="C2", reverse=False
+    )
+
+
+@image_comparison(
+    baseline_images=["reverse_overplotting"],
+    remove_text=True,
+    extensions=["png"],
+)
+def test_reverse_overplotting():
+    # Test overplotting with a reversed plot
+    labels = [r"$\theta_1$", r"$\theta_2$", r"$\theta_3$", r"$\theta_4$"]
+
+    figure = _run_corner(ndim=4, reverse=True, labels=labels)
+
+    # Set same results:
+    ndim, nsamples = 4, 10000
+    np.random.seed(1234)
+
+    data1 = np.random.randn(ndim * 4 * nsamples // 5).reshape(
+        [4 * nsamples // 5, ndim]
+    )
+    mean = 4 * np.random.rand(ndim)
+    data2 = mean[None, :] + np.random.randn(ndim * nsamples // 5).reshape(
+        [nsamples // 5, ndim]
+    )
+    samples = np.vstack([data1, data2])
+
+    value1 = mean
+    # This is the empirical mean of the sample:
+    value2 = np.mean(data1, axis=0)
+
+    corner.overplot_lines(figure, value1, color="C1", reverse=True)
+    corner.overplot_points(
+        figure, value1[None], marker="s", color="C1", reverse=True
+    )
+    corner.overplot_lines(figure, value2, color="C2", reverse=True)
+    corner.overplot_points(
+        figure, value2[None], marker="s", color="C2", reverse=True
+    )
+
+
 @image_comparison(
     baseline_images=["hist_bin_factor"], remove_text=True, extensions=["png"]
 )