{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "b0761131-44c3-46b5-96c3-d658c77b4fdf",
   "metadata": {
    "tags": []
   },
   "source": [
    "Strings - Slicing --- 5 min\n",
    "===\n",
    "\n",
    "* 5 min | Última modificación: Octubre 4, 2021"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "1cc18abc-0682-4662-92fb-3b3303a38acb",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "6"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "# La función len calcula la longitud de una cadena de caracteres.\n",
    "#\n",
    "s = \"Python\"\n",
    "len(s)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "5a8fbfd6-20a8-4fa3-bc1b-523330efc630",
   "metadata": {},
   "source": [
    "En Python, los strings son vectores de caracteres; el primer caracter ocupa la posición 0, el segundo la 1 y así sucesivamente. Los índices negativos (iniciando en `-1`) se usan para indicar la posición contando desde atrás. Por ejemplo: \n",
    " \n",
    "     +---+---+---+---+---+---+\n",
    "     | P | y | t | h | o | n |\n",
    "     +---+---+---+---+---+---+\n",
    "       0   1   2   3   4   5   \n",
    "      -6  -5  -4  -3  -2  -1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "f5bb9cb2-f9f0-462f-9e52-2fc17d80bf5b",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'P'"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "# Caracter en la posición 0\n",
    "#\n",
    "word = \"Python\"\n",
    "word[0]  # Primer caracter"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "547e0e6c-5436-461c-8d7d-efa6db205bea",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'n'"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "#\n",
    "# Caracter en la posición 5\n",
    "#\n",
    "word[5]  # Sexto caracter"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "69df2cba-5c52-43f1-9774-5f118f68087b",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'n'"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "#\n",
    "# Ultimo caracter\n",
    "#\n",
    "word[-1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "b5cc9d19-0d3e-4573-a3ca-af8ffb89ed1c",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'o'"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "# \n",
    "# Antepenúltimo caracter\n",
    "#\n",
    "word[-2]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "ef5896ae-c756-4ed0-b9df-16e648e605f5",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'P'"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "# \n",
    "# Primer caracter\n",
    "#\n",
    "word[-6]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "307a3572-dbda-4d8a-9044-59ed2cb58fda",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Py'"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "# \n",
    "# El operador `:` se usa para indicar rangos\n",
    "#\n",
    "word[0:2]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "ea553c9c-4fb3-4092-a005-b300c9e775e7",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Py'"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "# \n",
    "# ':2' indica desde el principio hasta la\n",
    "# posición 2 (sin incluirla)\n",
    "#\n",
    "word[:2]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "bc887492-9f8e-4072-a499-5f7f5ff403ca",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'tho'"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "# \n",
    "# Caracteres en las posiciones 2, 3 y 4\n",
    "#\n",
    "word[2:5]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "eb7cb9b7-9da8-4972-9f0a-ebd33391fce4",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'thon'"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "# \n",
    "# Desde la posición 2 hasta el final\n",
    "#\n",
    "word[2:]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "e97fbeb2-68f5-4c0d-bdf7-01c10dfd1723",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Python'"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "# \n",
    "# Hasta la posición 2 + De la posición 2 en adelante\n",
    "# \"Py\" + \"thon\"\n",
    "#\n",
    "word[:2] + word[2:]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "dd3ce2f0-98d0-42fb-80f2-a9fdc655bc5b",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'on'"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "# \n",
    "# Desde la posición -2 hasta el final,\n",
    "# o sea, los últimos dos caracteres.\n",
    "#\n",
    "word[-2:]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "id": "6e97abcd-ef40-4d2f-8b78-50ace5360ced",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'yth'"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#    +---+---+---+---+---+---+\n",
    "#    | P | y | t | h | o | n |\n",
    "#    +---+---+---+---+---+---+\n",
    "#      0   1   2   3   4   5   \n",
    "#     -6  -5  -4  -3  -2  -1\n",
    "# \n",
    "word[-5:-2]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "id": "3377a426-3892-4912-893b-57c026c5b1f1",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Python'"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "# Desde el primero hasta el último caracter.\n",
    "# Genera una copia\n",
    "#\n",
    "word[:]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "id": "85ecd63b-6804-424c-88f1-841ac815c245",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'hl ud re!'"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#  +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+\n",
    "#  | h | o | l | a |   | m | u | n | d | o |   | c | r | u | e | l |   | ! |\n",
    "#  +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+\n",
    "#    0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17\n",
    "# \n",
    "phrase = \"hola mundo cruel!\"\n",
    "\n",
    "phrase[::2]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "id": "891b44b8-7ed6-41f1-a2ad-9aeac93ea3a1",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'oamn'"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "#\n",
    "#  +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+\n",
    "#  | h | o | l | a |   | m | u | n | d | o |   | c | r | u | e | l |   | ! |\n",
    "#  +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+\n",
    "#    0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17\n",
    "# \n",
    "phrase = \"hola mundo cruel!\"\n",
    "\n",
    "phrase[1:9:2]"
   ]
  }
 ],
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