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  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Python3: Plotting of GOLEM $U_\\mathrm{loop}$ signal\n",
    "\n",
    "## Python3 source code\n",
    "- as Jupyter notebook: [Uloop.ipynb](./Uloop.ipynb)\n",
    "- as Python3 script (exported from this notebook): [Uloop.py](./Uloop.py)\n",
    "\n",
    "## Result (in Jupyter notebook format)\n",
    "Loading of basic libraries.\n",
    "The `matplotlib` library is used for plotting, the `pandas` library for data retrieval and manipulation. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# Basic libraries\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "import pandas as pd"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The parametrized URL address to obtain CSV files from the analysis results of the basic diagnostics"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "data_URL = 'http://golem.fjfi.cvut.cz/shots/{shot_no}/Diagnostics/BasicDiagnostics/Results/{name}.csv'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Discharge number to use. The special discharge number 0 refers to the most recent discharge"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "shot_no = 38778"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The processed loop voltage signal $U_\\mathrm{loop}$ is automatically downloaded and read using the Pandas library into a `pandas.Series` object from the specified URL."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "U_loop = pd.read_csv(data_URL.format(shot_no=shot_no, name='U_loop'),  # create a specific URL\n",
    "                     names=['time', 'U_loop'], # names of the columns\n",
    "                     index_col=0,  # first column will serve as index (independent variable) \n",
    "                     squeeze=True, # return as Series since there is only 1 dependent variable column\n",
    "                    )"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The `.plot()` wrapper method for plotting with the `matplotlib` library automatically selects the x and y values and the plot type (line for 1D). It returns an `Axes` object, which is then used to label the axes and set a title."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "ax = U_loop.plot()\n",
    "ax.set(title=\"GOLEM #{}\".format(shot_no), xlabel='time [ms]', ylabel=r'$U_\\mathrm{loop}$ [V]')\n",
    "plt.savefig('plot.jpg')"
   ]
  }
 ],
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