Fixed #979 Normalize subsequences before plotting

Author: seanlaw

docs/Tutorial_AB_Joins.ipynb

@@ -336,8 +336,11 @@
     }
    ],
    "source": [
-    "plt.plot(queen_df.iloc[queen_motif_index : queen_motif_index + m].values, label='Under Pressure')\n",
-    "plt.plot(vanilla_ice_df.iloc[vanilla_ice_motif_index:vanilla_ice_motif_index+m].values, label='Ice Ice Baby')\n",
+    "queen_z_norm_motif = core.z_norm(queen_df.iloc[queen_motif_index : queen_motif_index + m].values)\n",
+    "vanilla_ice_z_norm_motif = core.z_norm(vanilla_ice_df.iloc[vanilla_ice_motif_index:vanilla_ice_motif_index+m].values)\n",
+    "\n",
+    "plt.plot(queen_z_norm_motif, label='Under Pressure')\n",
+    "plt.plot(vanilla_ice_z_norm_motif, label='Ice Ice Baby')\n",
     "\n",
     "plt.xlabel('Time')\n",
     "plt.ylabel('Frequency')\n",
@@ -347,6 +350,26 @@
     "plt.show()"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "[comment]: <> (Myst)\n",
+    ":::{admonition} **Z-normalizing Your Subsequences Before Plotting**\n",
+    ":class: note\n",
+    "\n",
+    "By default, `stumpy` z-normalizes **all** subsequences before comparing their matrix profile distances (i.e., `normalize=True`). Thus, before we visualize the matching subsequences, we must also z-normalize them first. Failure to do so would result in subsequences being plotted with non-normalized amplitudes. Subsequence z-normalization can be easily accomplished by using the `core.z_norm` helper function:\n",
+    "\n",
+    "```\n",
+    "from stumpy import core\n",
+    "\n",
+    "core.z_norm(T[idx : idx + m])\n",
+    "```\n",
+    "\n",
+    "However, this z-normalization step should be omitted whenever the `normalize` parameter has been set to `False` when computing matrix profile distances.\n",
+    ":::"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -385,7 +408,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.12.3"
+   "version": "3.12.4"
   }
  },
  "nbformat": 4,