09_Funciones_Avanzadas_2018.ipynb

{
 "cells": [
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   "cell_type": "markdown",
   "metadata": {
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   },
   "source": [
    "<img src=\"images/utfsm.png\" alt=\"\" width=\"200px\" align=\"right\"/>\n",
    "\n",
    "<br/>\n",
    "\n",
    "# IWI131 Programación\n",
    "Funciones Avanzadas<br/>\n",
    "Cristopher Arenas<br/>\n",
    "cristopher.arenas@usm.cl<br/>\n",
    "\n",
    "<br/>\n",
    "Paralelo 204<br/>\n",
    "Campus San Joaquin"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true,
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "### 1. Módulos"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "Un módulo es una colección de definiciones de variables, funciones y tipos (entre otras cosas) que pueden ser importadas para ser usadas desde cualquier programa."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0.5\n",
      "7.38905609893\n",
      "3.14159265359\n",
      "7.38905609893\n"
     ]
    }
   ],
   "source": [
    "from math import exp,cos\n",
    "from math import pi, e\n",
    "print cos(pi/3)\n",
    "print exp(2)\n",
    "print pi\n",
    "print e**2"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "**Ventajas**\n",
    "- Funciones y variables solo deben ser definidas una sola vez.\n",
    "- Organización del programa en secciones lógicas.\n",
    "- Es más fácil compartir componentes con otros programadores."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "**Algunos Módulos en Python**\n",
    "- Módulo `math`\n",
    "- Módulo `random`\n",
    "- Módulo `turtle`"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "**Importación de Nombres**"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "1. Usar  `from` modulo `import` nombres:\n",
    " ```Python\n",
    " from math import sin,cos\n",
    " ```\n",
    " Luego, las funciones se llaman como: `sin(10)` y `cos(20)`. <br/> <br/>\n",
    "2. Usar `import` modulo:\n",
    " ```Python\n",
    " import math\n",
    " ```\n",
    " Luego, las funciones se llaman como: `math.sin(10)` y `math.cos(20)`. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "-0.544021110889\n",
      "0.408082061813\n"
     ]
    }
   ],
   "source": [
    "from math import sin,cos\n",
    "print sin(10)\n",
    "print cos(20)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "-0.544021110889\n",
      "0.408082061813\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "print math.sin(10)\n",
    "print math.cos(20)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "La forma menos complicada de importar funciones:\n",
    "\n",
    "```Python\n",
    "from modulo import *\n",
    "```"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [],
   "source": [
    "from random import *"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 86,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "20"
      ]
     },
     "execution_count": 86,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#entrega un numero al azar entre 0 y 1\n",
    "int(1000*random())%40"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 78,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "19"
      ]
     },
     "execution_count": 78,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "randrange(1,40)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 94,
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "lista con elementos\n",
      "[1, 2, 5, 10, 'a', [1, 2]]\n",
      "sacar un elemento de la lista al azar\n",
      "10\n",
      "lista sin el elemento seleccionado\n",
      "[1, 2, 5, 'a', [1, 2]]\n"
     ]
    }
   ],
   "source": [
    "l = [1,2,5,10,\"a\",[1,2]]\n",
    "print \"lista con elementos\"\n",
    "print l\n",
    "a = choice(l)\n",
    "print \"sacar un elemento de la lista al azar\"\n",
    "print a\n",
    "l.remove(a)\n",
    "print \"lista sin el elemento seleccionado\"\n",
    "print l"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "#### Creación de módulos"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "- Crear archivo nombre.py\n",
    "- Definir funciones\n",
    "- Desde otro archivo .py llamar al módulo **nombre** y las funciones creadas podrán usarse"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "### 2. Tipos de retorno"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "Una función puede retornar **un valor**, **muchos valores** o **ningun valor**"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "¿Qué retornan las siguientes funciones?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [],
   "source": [
    "def convertir_segundos(segundos):\n",
    "    horas = segundos/3600\n",
    "    minutos = (segundos/60)%60\n",
    "    segundos = segundos%60\n",
    "    return horas, minutos, segundos"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 1, 50)\n"
     ]
    }
   ],
   "source": [
    "c = convertir_segundos(3710)\n",
    "print c"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [],
   "source": [
    "h,m,s = convertir_segundos(3710)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "1\n",
      "50\n"
     ]
    }
   ],
   "source": [
    "print h\n",
    "print m\n",
    "print s"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "outputs": [],
   "source": [
    "def imprimir_datos(nombre,apellido,rol,dia,mes,anno):\n",
    "    print \"Nombre completo:\",nombre,apellido\n",
    "    print \"Rol:\",rol\n",
    "    print \"Fecha de nacimiento:\",dia,\"/\",mes,\"/\",anno"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Nombre completo: Perico Los Palotes\n",
      "Rol: 201653182-4\n",
      "Fecha de nacimiento: 3 / 1 / 1996\n"
     ]
    }
   ],
   "source": [
    "imprimir_datos(\"Perico\",\"Los Palotes\",\"201653182-4\",3,1,1996)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Nombre completo: Perico Los Palotes\n",
      "Rol: 201653182-4\n",
      "Fecha de nacimiento: 3 / 1 / 1996\n"
     ]
    }
   ],
   "source": [
    "a = imprimir_datos(\"Perico\",\"Los Palotes\",\"201653182-4\",3,1,1996)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "None\n"
     ]
    }
   ],
   "source": [
    "print a"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "### 3. Parámetros con valores por defecto"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "Al definir funciones, se pueden establecer valores determinados para ciertos parámetros. Al omitir estos parámetros en la llamada a la función, se utilizará el valor por defecto."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 95,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [],
   "source": [
    "def f(a,b=2,c=3):\n",
    "    return a+b+c"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "¿Qué pasa en los siguientes casos?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 96,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "15"
      ]
     },
     "execution_count": 96,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "f(10)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 97,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "28"
      ]
     },
     "execution_count": 97,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "f(10,15)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 98,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "f() takes at least 1 argument (0 given)",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-98-c43e34e6d405>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mf\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: f() takes at least 1 argument (0 given)"
     ]
    }
   ],
   "source": [
    "f()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "¿los parámetros por defecto pueden ir al inicio en la definición de las funciones?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 103,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "non-default argument follows default argument (<ipython-input-103-837e7fc2d36e>, line 1)",
     "output_type": "error",
     "traceback": [
      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-103-837e7fc2d36e>\"\u001b[0;36m, line \u001b[0;32m1\u001b[0m\n\u001b[0;31m    def f2(a=3,b):\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m non-default argument follows default argument\n"
     ]
    }
   ],
   "source": [
    "def f2(a=3,b):\n",
    "    return a*b\n",
    "\n",
    "p = f2(4,5)\n",
    "print p"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "### 4. Funciones como parámetros"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "Al definir funciones es posible pasar como parámetro de una función, otra función."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 104,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [],
   "source": [
    "def sumar(n,f):\n",
    "    s = 0\n",
    "    for i in range(n):\n",
    "        s = s+f(i)\n",
    "    return s\n",
    "\n",
    "def identidad(x):\n",
    "    return x\n",
    "\n",
    "def cuadrado(x):\n",
    "    return x**2\n",
    "\n",
    "def cubo(x):\n",
    "    return x**3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 105,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "45\n"
     ]
    }
   ],
   "source": [
    "print sumar(10,identidad)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 106,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "285\n"
     ]
    }
   ],
   "source": [
    "print sumar(10,cuadrado)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 107,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2025\n"
     ]
    }
   ],
   "source": [
    "print sumar(10,cubo)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "### 5. Funciones Recursivas"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "Ocurre cuando una función puede ser llamada dentro de si misma. Debe haber una condición que ponga fin a la recursión."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 108,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [],
   "source": [
    "def factorial(n):\n",
    "    if n==0:\n",
    "        return 1\n",
    "    else:\n",
    "        return n*factorial(n-1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 109,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "6"
      ]
     },
     "execution_count": 109,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "factorial(3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 111,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [
    {
     "ename": "RuntimeError",
     "evalue": "maximum recursion depth exceeded",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mRuntimeError\u001b[0m                              Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-111-4ce693157c84>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mfactorial\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m-\u001b[0m\u001b[0;36m10\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;32m<ipython-input-108-999bf21a2502>\u001b[0m in \u001b[0;36mfactorial\u001b[0;34m(n)\u001b[0m\n\u001b[1;32m      3\u001b[0m         \u001b[0;32mreturn\u001b[0m \u001b[0;36m1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      4\u001b[0m     \u001b[0;32melse\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 5\u001b[0;31m         \u001b[0;32mreturn\u001b[0m \u001b[0mn\u001b[0m\u001b[0;34m*\u001b[0m\u001b[0mfactorial\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mn\u001b[0m\u001b[0;34m-\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "... last 1 frames repeated, from the frame below ...\n",
      "\u001b[0;32m<ipython-input-108-999bf21a2502>\u001b[0m in \u001b[0;36mfactorial\u001b[0;34m(n)\u001b[0m\n\u001b[1;32m      3\u001b[0m         \u001b[0;32mreturn\u001b[0m \u001b[0;36m1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      4\u001b[0m     \u001b[0;32melse\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 5\u001b[0;31m         \u001b[0;32mreturn\u001b[0m \u001b[0mn\u001b[0m\u001b[0;34m*\u001b[0m\u001b[0mfactorial\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mn\u001b[0m\u001b[0;34m-\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mRuntimeError\u001b[0m: maximum recursion depth exceeded"
     ]
    }
   ],
   "source": [
    "factorial(-10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "source": [
    "¿Se parece la recursión a un ciclo while?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "slideshow": {
     "slide_type": "skip"
    }
   },
   "outputs": [],
   "source": []
  }
 ],
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