cas-pml/SL/aufgaben/template/4_WS/WS 15 Vorlage.ipynb

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    "# WS 15 Schwellenwert für Accuracy"
   ]
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    "* `.predict_proba()` gibt bei allen Klassifikatoren die Wahrscheinlichkeit für die Zugehörigkeit zu den einlenen Klassen zurück, `predict()` dagegen die wahrscheinlichtste Klasse selber\n",
    "* für Zwei-Klassen Fragestellungen bedeutet dies, dass bei einer Wahrscheinlickkeit (proba) `> 0.5` für die erste Klasse diese zurückgegeben wird, andernfalls die zweite Klasse, `0.5` ist somit ein scheinbar willkürlicher Schwellenwert\n",
    "* untersuchen Sie die Auswirkung anderer Schwellenwerte auf die Accuracy mit `RandomForestClassifier` auf den aufbereiteten Bankkunden-Datan\n",
    "\n",
    "* vorgeschlagenes Vorgehen:\n",
    "  * trainieren eines RandomForestClassifier mit den vorbereiteten Bankkundendaten (Trainingsdaten)\n",
    "  * bestimmen der Wahrscheinlichkeit für jede Beobachtung der entsprechenden Testdaten zur Klasse 'no'\n",
    "  * erstellen einens Range der zu untersuchenden Schwellenwerte, z.B. mit np.arange()\n",
    "  * in einem Loop über alle Werte dieses Ranges\n",
    "    * `y_pred` für den jeweiligen Schwellenwert berechnen (wiederum als `['no', 'yes']`)\n",
    "    * `accuracy_score()` der jeweiligen Prediction (und sammeln in einer Liste)\n",
    "  * ausgeben des besten Score-Wertes und des zugehörigen Schwellenwertes in der Konsole\n",
    "  * visualisieren der Ergebnisse auch als Lineplot  "
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   "source": [
    "## prepare env, read and prepare data\n",
    "import pandas as pd\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "import seaborn as sns; sns.set()\n",
    "\n",
    "codepath = '../2_code' ## for import of user defined module\n",
    "datapath = '../3_data'\n",
    "\n",
    "from sys import path; path.insert(1, codepath)\n",
    "from os import chdir; chdir(datapath)\n",
    "\n",
    "from bfh_cas_pml import prep_data\n",
    "X_train, X_test, y_train, y_test = prep_data('bank_data_prep.csv', target='y', seed=1234)"
   ]
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     "start_time": "2020-04-15T21:03:01.844142Z"
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   "source": [
    "## train a model\n",
    "from sklearn.ensemble import RandomForestClassifier \n",
    "model = RandomForestClassifier(random_state=1234)\n",
    "model.fit(X_train, y_train) \n",
    "\n",
    "## prediction using .predict_proba()\n",
    "y_pred_p_no = model.predict_proba(X_test)[:, 0]"
   ]
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   "execution_count": 5,
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     "text": [
      "0.0\n",
      "0.1\n",
      "0.2\n",
      "0.30000000000000004\n",
      "0.4\n",
      "0.5\n",
      "0.6000000000000001\n",
      "0.7000000000000001\n",
      "0.8\n",
      "0.9\n",
      "1.0\n"
     ]
    }
   ],
   "source": [
    "## inspect different threshold values\n",
    "from sklearn.metrics import accuracy_score\n",
    "\n",
    "thresholds = np.arange(0, 1.01, 0.1) ## test over 10\n",
    "#thresholds = np.arange(0, 1.01, 0.01)\n",
    "\n",
    "scores = []\n",
    "\n",
    "for threshold in thresholds:\n",
    "    ## tbd\n",
    "    print(threshold)\n",
    "\n",
    "    \n",
    "    "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
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   "source": [
    "## results\n",
    "## tbd\n",
    "\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
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   "source": [
    "## viszalization\n",
    "## tbd\n",
    "\n",
    "\n"
   ]
  }
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