Added graphical reduction toy example

sans/CreateConvertPlotExample.ipynb

@@ -0,0 +1,165 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Data manpulation widgets toy examples"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "scrolled": true
+   },
+   "outputs": [],
+   "source": [
+    "from example_widgets import ProcessWidget, PlotWidget, fake_load, setup_code_hiding, allowed_dimensions, filepath_converter\n",
+    "import scipp as sc\n",
+    "import functools\n",
+    "\n",
+    "# Workaround for the fact that you can't raise directly in tertiary expressions.\n",
+    "def raise_(ex):\n",
+    "    raise ex\n",
+    "\n",
+    "setup_code_hiding()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "plot_widget = PlotWidget(globals())"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Data Loading\n",
+    "Currently creates some example data rather than loading a file. The created file is a histogrammed time of flight data."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "data_creation = ProcessWidget(globals(), fake_load, 'Load', {'filepath': filepath_converter}, {'filepath': 'run number or file name'})\n",
+    "data_creation.subscribe(plot_widget)\n",
+    "data_creation"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Data conversion\n",
+    "This converts one physical dimension to another the current conversions support in scipp.neutron are:\n",
+    "* tof -> dspacing, wavelength, E\n",
+    "* d-spacing -> tof\n",
+    "* wavelength -> Q, tof\n",
+    "* E -> tof\n",
+    "* Q -> wavelength"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "scrolled": true
+   },
+   "outputs": [],
+   "source": [
+    "dim_converter = lambda dim : dim if dim in allowed_dimensions else raise_(ValueError(\n",
+    "    f'{dim} not an allowed dimension. Supported dimensions are {list(dimesion_to_unit.keys())}'))\n",
+    "data_converter = lambda name : globals()[name] if (name in globals()) else raise_(ValueError(\n",
+    "    f'{name} does not exist in notebook.'))\n",
+    "data_options = lambda : [\n",
+    "            key for key, item in globals().items()\n",
+    "            if isinstance(item, (sc.DataArray, sc.Dataset, sc.Variable))\n",
+    "        ]\n",
+    "\n",
+    "data_conversion = ProcessWidget(globals(), \n",
+    "                                  sc.neutron.convert, 'Convert', \n",
+    "                                  {'data': data_converter,\n",
+    "                                   'from' : dim_converter, 'to': dim_converter},\n",
+    "                                   options={'from' : allowed_dimensions,\n",
+    "                                            'to': allowed_dimensions,\n",
+    "                                            'data': data_options})\n",
+    "data_conversion.subscribe(plot_widget)\n",
+    "data_conversion"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Can also specify just some inputs of a function graphically."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Workaround because python doesn't like shadowing of from\n",
+    "kwargs = {'from':'tof'}\n",
+    "convert_tof = functools.partial(sc.neutron.convert, **kwargs)\n",
+    "data_conversion_tof = ProcessWidget(globals(), \n",
+    "                                  convert_tof, 'Convert from tof', \n",
+    "                                  {'data': data_converter,\n",
+    "                                   'to': dim_converter}, \n",
+    "                                   options={'to': allowed_dimensions,\n",
+    "                                            'data': data_options})\n",
+    "data_conversion_tof.subscribe(plot_widget)\n",
+    "data_conversion_tof"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Data plotting\n",
+    "Plots the data aquired by evaluating the expression entered."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "scrolled": false
+   },
+   "outputs": [],
+   "source": [
+    "plot_widget"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.7.8"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}