added FCA example

FCA.ipynb

+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "economic-poker",
+   "metadata": {},
+   "source": [
+    "# FCA & DraCor\n",
+    "\n",
+    "We want to analyse which characters speak in scenes of different plays. Therefore, we extract the corresponding information from [DraCor](https://dracor.org/) and analyse it using [Formal Concept Analysis](https://www.upriss.org.uk/fca/fca.html).\n",
+    "\n",
+    "## DraCor\n",
+    "\n",
+    "[This simple Python library](https://pypi.org/project/dracor/) allows us to download and process plays from [DraCor](https://dracor.org/). Specifically, it allows us to extract information about which character speaks in which scene."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "legislative-disclaimer",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "!pip install dracor"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "finite-introduction",
+   "metadata": {},
+   "source": [
+    "Let us now download a play and extract the speaker information from the scenes:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "regular-arthur",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import dracor\n",
+    "play = dracor.play(\"shake\", \"a-midsummer-night-s-dream\")\n",
+    "scenes = dracor.scenes(play)\n",
+    "scenes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "protecting-spare",
+   "metadata": {},
+   "source": [
+    "([more Shakespeare plays](https://dracor.org/shake) or [German plays](https://dracor.org/ger))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "virgin-administration",
+   "metadata": {},
+   "source": [
+    "## Formal Concept Analysis (FCA)\n",
+    "\n",
+    "To create a [context](https://concepts.readthedocs.io/en/latest/api.html#context), we need a list of *objects* (we use the scenes of the play), a list of *attributes* (we use the characters of the play), and an *incidence relation* between them (in our example whether a character appears in a scene):"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "urban-alloy",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "objects = play_scenes.keys()\n",
+    "\n",
+    "attributes = set()\n",
+    "for scene, speakers in othello_scenes.items():\n",
+    "    attributes.update(speakers)\n",
+    "attributes = sorted(attributes)\n",
+    "\n",
+    "incidence = [tuple([a in othello_scenes[o] for a in attributes]) for o in objects]"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "communist-element",
+   "metadata": {},
+   "source": [
+    "Now we can create a formal context and compute the number of formal concepts:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "grave-hungary",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import concepts\n",
+    "\n",
+    "ctx = concepts.Context(objects, attributes, incidence)\n",
+    "len(ctx.lattice)                                       # the number of formal concepts"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "hungry-vulnerability",
+   "metadata": {},
+   "source": [
+    "Finally, we can (try to) visualize the concept lattics:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "piano-practice",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "ctx.lattice.graphviz()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "announced-lawsuit",
+   "metadata": {},
+   "source": [
+    "... and save the context:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "organic-cable",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "ctx.tofile(\"play.cxt\", frmat=\"cxt\")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "muslim-charity",
+   "metadata": {},
+   "source": [
+    "Let's test some other examples. Choose a play from the list below (recommendations: [ger/goethe-iphigenie-auf-tauris](https://dracor.org/ger/goethe-iphigenie-auf-tauris), [shake/a-midsummer-night-s-dream](https://dracor.org/shake/a-midsummer-night-s-dream)):"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "interior-steam",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from ipywidgets import interact, Dropdown\n",
+    "import dracor\n",
+    "\n",
+    "corpora = dracor.corpora()\n",
+    "\n",
+    "corpus_widget = Dropdown(options=corpora, value='shake', description='Corpus:')\n",
+    "play_widget = Dropdown(options=dracor.plays(\"shake\"), value=\"a-midsummer-night-s-dream\", description='Play:')\n",
+    "\n",
+    "def on_update_corpus_widget(*args):\n",
+    "    play_widget.options = dracor.plays(corpus_widget.value)\n",
+    "\n",
+    "corpus_widget.observe(on_update_corpus_widget, 'value')\n",
+    "\n",
+    "@interact(corpus=corpus_widget, play=play_widget)\n",
+    "def visualize_play_lattice(corpus, play):\n",
+    "    \"\"\"Compute the lattice for the given play, show it, and save it in a file.\"\"\"\n",
+    "    scenes = dracor.scenes(dracor.play(corpus, play))\n",
+    "    \n",
+    "    # extract formal context (G, M, I) = (objects, attributes, incidence)\n",
+    "    objects = scenes.keys()\n",
+    "\n",
+    "    attributes = set()\n",
+    "    for scene, speakers in scenes.items():\n",
+    "        attributes.update(speakers)\n",
+    "    attributes = sorted(attributes)\n",
+    "\n",
+    "    incidence = [tuple([a in scenes[o] for a in attributes]) for o in objects]\n",
+    "    \n",
+    "    ctx = concepts.Context(objects, attributes, incidence)\n",
+    "    \n",
+    "    print(len(ctx.lattice), \"formal concepts\")\n",
+    "    ctx.tofile(play + \".cxt\", frmat=\"cxt\")\n",
+    "    \n",
+    "    return ctx.lattice.graphviz()"
+   ]
+  }
+ ],
+ "metadata": {
+  "language_info": {
+   "name": "python",
+   "pygments_lexer": "ipython3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}