DOC: Add version switcher to the documentation (#21426)

2 files changed, 74 insertions, 0 deletions

diff --git a/doc/source/_static/versions.json b/doc/source/_static/versions.json
new file mode 100644
index 000000000..104a30de7
--- /dev/null
+++ b/doc/source/_static/versions.json
@@ -0,0 +1,62 @@
+[
+    {
+        "name": "dev",
+        "version": "devdocs",
+        "url": "https://numpy.org/devdocs/"
+    },
+    {
+        "name": "1.22 (stable)",
+        "version": "stable",
+        "url": "https://numpy.org/doc/stable/"
+    },
+    {
+        "name": "1.22",
+        "version": "1.22",
+        "url": "https://numpy.org/doc/1.22/"
+    },
+    {
+        "name": "1.21",
+        "version": "1.21",
+        "url": "https://numpy.org/doc/1.21/"
+    },
+    {
+        "name": "1.20",
+        "version": "1.20",
+        "url": "https://numpy.org/doc/1.20/"
+    },
+    {
+        "name": "1.19",
+        "version": "1.19",
+        "url": "https://numpy.org/doc/1.19/"
+    },
+    {
+        "name": "1.18",
+        "version": "1.18",
+        "url": "https://numpy.org/doc/1.18/"
+    },
+    {
+        "name": "1.17",
+        "version": "1.17",
+        "url": "https://numpy.org/doc/1.17/"
+    },
+    {
+        "name": "1.16",
+        "version": "1.16",
+        "url": "https://numpy.org/doc/1.16/"
+    },
+    {
+        "name": "1.15",
+        "version": "1.15",
+        "url": "https://numpy.org/doc/1.15/"
+    },
+    {
+        "name": "1.14",
+        "version": "1.14",
+        "url": "https://numpy.org/doc/1.14/"
+    },
+    {
+        "name": "1.13",
+        "version": "1.13",
+        "url": "https://numpy.org/doc/1.13/"
+    }
+]
diff --git a/doc/source/conf.py b/doc/source/conf.py
index 4301fe553..1a201a3c5 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -171,6 +171,12 @@ html_logo = '_static/numpylogo.svg'
 
 html_favicon = '_static/favicon/favicon.ico'
 
+# Set up the version switcher.  The versions.json is stored in the devdocs.
+if ".dev" in version:
+    switcher_version = "devdocs"
+else:
+    switcher_version = f"doc/{version}"
+
 html_theme_options = {
   "logo_link": "index",
   "github_url": "https://github.com/numpy/numpy",
@@ -179,6 +185,12 @@ html_theme_options = {
   "external_links": [
       {"name": "Learn", "url": "https://numpy.org/numpy-tutorials/"}
       ],
+  # Add light/dark mode and documentation version switcher:
+  "navbar_end": ["version-switcher", "navbar-icon-links"],
+  "switcher": {
+      "version_match": switcher_version,
+      "json_url": "https://numpy.org/devdocs/_static/versions.json",
+  },
 }
 
 html_title = "%s v%s Manual" % (project, version)