slovniky.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Slovníky -- dict()\n",
    "\n",
    "Tento datový typ implementuje tzv. [asociativní pole](https://cs.wikipedia.org/wiki/Asociativn%C3%AD_pole). Položky v&nbsp;kolekci nejsou indexovány pomocí celočíselných indexů, ale pomocí klíčů.\n",
    "Klíčem může být některý s neměnitelných datových typů. Datový type `dict` je\n",
    "ale **měnitelný**.\n",
    "\n",
    "Zapisuje se do složených závorek `{}` vždy jako dvojice `klíč:hodnota`.\n",
    "Pokud je při přiřazení použit klíč, který neexistuje vytvoří se."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{1: 'ahoj', 'neco': 3.14, 'slovo': 1}"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d = {1: 'ahoj', 'neco': 3.14, 'slovo': 1}\n",
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{1: 'ahoj', 'neco': 3.14, 'slovo': 1}"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d = {}\n",
    "d['slovo'] = 1\n",
    "d['neco'] = 3.14\n",
    "d[1] = 'ahoj'\n",
    "d"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "* Slovník `dict()` podporuje operátor příslušnosti `in`, počet prvků lze zjistit pomocí funkce `len()` a slovníky mezi sebou lze porovnat pomocí operátorů `==` a `!=`.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "2"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d = {1: 'ahoj', 'cislo': 3.14}\n",
    "len(d)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "3.14 in d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "'cislo' in d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "{1: 'ahoj', 'cislo': 3.14} == {1: 'ahoj', 'cislo': 3.14}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "{2: 'ahoj', 'cislo': 3.14} == {1: 'ahoj', 'cislo': 3.14}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "{1: 'ahojjj', 'cislo': 3.14} == {1: 'ahoj', 'cislo': 3.14}"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "* Slovníky lze procházet. Stejně jako při testování pomocí `in` se prochází *klíče*, nikoli hodnoty.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "cislo\n"
     ]
    }
   ],
   "source": [
    "for k in {1: 'ahojjj', 'cislo': 3.14}:\n",
    "    print(k)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "* **Spojování slovníků** se děje pomocí metody `.updte()` nebo pomocí funkce `dict()`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'a': 123, 'b': 985, 'jmeno': 'Karel', 'prijmeni': 'Novak'}"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d1 = {'a': 123, 'b': 985}\n",
    "dict(d1, jmeno='Karel', prijmeni='Novak')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Nebo lze použít operátor `**`, který slovník rozbalí."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'a': 123, 'b': 985, 'jmeno': 'Karel', 'prijmeni': 'Novak'}"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d1 = {'a': 123, 'b': 985}\n",
    "d2 = {'jmeno': 'Karel', 'prijmeni':'Novak'}\n",
    "dict(d1, **d2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "další možnost:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "d1 = {'a': 123, 'b': 985}\n",
    "d2 = {'jmeno': 'Karel', 'prijmeni':'Novak'}\n",
    "d = {}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'a': 123, 'b': 985}"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.update(d1)\n",
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'a': 123, 'b': 985, 'jmeno': 'Karel', 'prijmeni': 'Novak'}"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.update(d2)\n",
    "d"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Některé zajímavé metody\n",
    "\n",
    "metoda |\n",
    ":------|:-------\n",
    "`d.has_key(k)` | Vrátí `True` nebo `False` pokud slovník `d` obsahuje nebo neobsahuje klíč `k`.\n",
    "`d.keys()` | Vrátí pohled tvořený všemi klíči.\n",
    "`d.values()` | Vrátí pohled tvořený všemi hodnotami.\n",
    "`d.items()` | Vrátí pohled tvořený všemi dvojicemi `(klíč,hodnota)`.\n",
    "`d.get(k)` | Vrátí hodnotu spojenou s klíčem `k` nebo `None` pokud klíč neexistuje.\n",
    "`d.get(k,v)` | Vrátí hodnotu spojenou s klíčem `k` nebo `v` pokud klíč neexistuje.\n",
    "`d.popitem()` | Odstraní náhodnou položku/hodnotu a vrátí ji jako *pohled*.\n",
    "`d.pop(k)` | Odstraní položku spojenou s klíčem `k` a vrátí její hodnotu.\n",
    "`d.pop(k,v)` |Odstraní položku spojenou s klíčem `k` a vrátí její hodnotu. Pokud klíč neexistuje vrátí `v`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 43,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{1: 'ahoj', 2: 'nazdar', 'cislo': 3.14, 'jmeno': 'Karel'}"
      ]
     },
     "execution_count": 43,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d={}\n",
    "d['cislo']=3.14\n",
    "d['jmeno']='Karel'\n",
    "d[1]='ahoj'\n",
    "d[2]='nazdar'\n",
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "dict_values(['Karel', 'ahoj', 'nazdar', 3.14])"
      ]
     },
     "execution_count": 44,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.values()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 45,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "dict_keys(['jmeno', 1, 2, 'cislo'])"
      ]
     },
     "execution_count": 45,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.keys()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 46,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "dict_items([('jmeno', 'Karel'), (1, 'ahoj'), (2, 'nazdar'), ('cislo', 3.14)])"
      ]
     },
     "execution_count": 46,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.items()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "jmeno : Karel\n",
      "1 : ahoj\n",
      "2 : nazdar\n",
      "cislo : 3.14\n"
     ]
    }
   ],
   "source": [
    "for klic, hodnota in d.items():\n",
    "    print(klic, \":\", hodnota)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 48,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Karel'"
      ]
     },
     "execution_count": 48,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.get('jmeno')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 49,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "d.get('HogoFogo')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 50,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "59"
      ]
     },
     "execution_count": 50,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.get('HogoFogo',59)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 51,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{1: 'ahoj', 2: 'nazdar', 'cislo': 3.14, 'jmeno': 'Karel'}"
      ]
     },
     "execution_count": 51,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 52,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'nazdar'"
      ]
     },
     "execution_count": 52,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.pop(2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 53,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{1: 'ahoj', 'cislo': 3.14, 'jmeno': 'Karel'}"
      ]
     },
     "execution_count": 53,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 54,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'neni tu'"
      ]
     },
     "execution_count": 54,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.pop(777,'neni tu')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 55,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "('jmeno', 'Karel')"
      ]
     },
     "execution_count": 55,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.popitem()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 56,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{1: 'ahoj', 'cislo': 3.14}"
      ]
     },
     "execution_count": 56,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 57,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(1, 'ahoj')"
      ]
     },
     "execution_count": 57,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d.popitem()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
 ],
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