Added QuadMesh element example

examples/elements/bokeh/QuadMesh.ipynb

@@ -0,0 +1,106 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<div class=\"contentcontainer med left\" style=\"margin-left: -50px;\">\n",
+    "<dl class=\"dl-horizontal\">\n",
+    "  <dt>Title</dt> <dd> QuadMesh Element</dd>\n",
+    "  <dt>Dependencies</dt> <dd>Bokeh</dd>\n",
+    "  <dt>Backends</dt> <dd>[Bokeh](./QuadMesh.ipynb)</dd> <dd>[Matplotlib](../matplotlib/QuadMesh.ipynb)</dd>\n",
+    "</dl>\n",
+    "</div>"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import numpy as np\n",
+    "import holoviews as hv\n",
+    "hv.notebook_extension('bokeh', 'matplotlib')"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The basic ``QuadMesh`` is a 2D grid of bins specified as x-/y-values specifying a regular sampling or edges, with arbitrary sampling and an associated 2D array containing the bin values. The coordinate system of a ``QuadMesh`` is defined by the bin edges, therefore any index falling into a binned region will return the appropriate value. Since a ``QuadMesh`` can define arbitrary bin widths it can define any arbitrary sampling, such as a log scale:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "%%opts QuadMesh [tools=['hover']]\n",
+    "n = 8\n",
+    "xs = np.logspace(1, 3, n)\n",
+    "ys = np.linspace(1, 10, n)\n",
+    "zs = np.arange((n-1)**2).reshape(n-1, n-1)\n",
+    "qmesh = hv.QuadMesh((xs, ys, zs))\n",
+    "\n",
+    "qmesh + qmesh(plot=dict(logx=True))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Unlike ``Image`` objects, slices must be inclusive of the bin edges, otherwise the slicing semantics work just the same as in an Image. We can provide slices along the x- and y-axis to get a slice of the lower corner. To keep the same color range above we set the z-dimension range:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "qmesh[20:400, :8].redim.range(z=qmesh.range('z'))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Since we can reveal the values with a hover tool a QuadMesh can be used as an overlay which reveals the value on hover simply by casting the Image to a QuadMesh. By setting the ``alpha`` to 0 and defining a hover alpha and color we can highlight the selected value on hover:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "%%opts QuadMesh [tools=['hover']] (alpha=0 hover_line_alpha=1 hover_line_color='black')\n",
+    "img = hv.Image(np.random.rand(10,10))\n",
+    "img * hv.QuadMesh(img)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python [conda env:science]",
+   "language": "python",
+   "name": "conda-env-science-py"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}