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   "cell_type": "markdown",
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   "source": [
    "## Event file Header information ##\n",
    "\n",
    "Header information is stored internally in aanet, in a class called Head,\n",
    "in a way that derives directly from the ascii (.evt) event files. The EventFile \n",
    "class loads the header automatically from the event file:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
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    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<class '__main__.Head'>\n",
      "start_run:  1\n",
      "PDF: 4      58\n",
      "XSecFile:  \n",
      "can:  -479.9 545.21 1327.95\n",
      "coord_origin:  0 0 479.9 \n",
      "cut_in:  0 0 0 0\n",
      "cut_nu:  100 1e+07 -1 1\n",
      "cut_primary:  0 0 0 0\n",
      "cut_seamuon:  0 0 0 0\n",
      "detector:  /pi1/data/shanidze/km3net/TDR/DETECTORS/km3net_wpd_V2.det\n",
      "drawing: Volume\n",
      "genhencut:  3000 0\n",
      "genvol:  -22772.9 3161.5 26837.2 5.868e+13 2e+08\n",
      "kcut: 2\n",
      "livetime:  0 0\n",
      "model: 1       2       1       1      10\n",
      "muon_desc_file:  \n",
      "norma:  0 0\n",
      "nuflux: 0       2       0 0.500E+00 0.000E+00 0.200E+01 0.800E+01\n",
      "physics:  GENHEN 5.02-280602 110117 1754\n",
      "seed: GENHEN 3       1000 309408948         0\n",
      "simul:     \n",
      "spectrum:  -1.4\n",
      "target:  isoscalar\n",
      "end_event:\n",
      "\n",
      "ttt 0x9bb1890\r\n",
      " EventFile io / wall time = 0.095469 / 68553.3 (0.000139262 % spent on io.)\r\n"
     ]
    }
   ],
   "source": [
    "import ROOT\n",
    "import aa\n",
    "f = EventFile(\"../evtfiles/numu_jgandalf.root\")\n",
    "print type(f.header)\n",
    "print f.header \n",
    "    "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "You can access each line, like so (the result is always a string)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false,
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      " /pi1/data/shanidze/km3net/TDR/DETECTORS/km3net_wpd_V2.det\n"
     ]
    }
   ],
   "source": [
    "print f.header.get_line(\"detector\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "Some lines in the header have multiple, space separated, fields. For example, the genvol tag lists four \n",
    "numbers:\n",
    "(see http://pi1241.physik.uni-erlangen.de:8080/job/aanet_trunk/doxygen/Head_8hh_source.html#l00189\n",
    "for a list of field names that aanet knows about). You get the line genvol and parse the full line, or use the get_field method to get the number you need by name. In both cases, converting to a float is up to you."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      " -22772.9 3161.5 26837.2 5.868e+13 2e+08\n",
      "200000000.0\n",
      "200000000.0\n"
     ]
    }
   ],
   "source": [
    "print f.header.get_line(\"genvol\")\n",
    "\n",
    "print float( f.header.get_line(\"genvol\").split()[4] ) # numberofEvents is 4th number\n",
    "\n",
    "print float( f.header.get_field(\"genvol\",\"numberOfEvents\") )"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
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