02-Cap03-List-Comprehensions-Funcoes-Lambda.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## List Comprehension - Filtros e Mapeamentos"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "A utilização de list comprehension em Python é muito comum. List comprehension é a forma que Python utiliza para realizar filtros e mapeamentos, semelhante ao que vimos com as funções filter() e map()."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Definindo um array com a função bulti-in range()\n",
    "array1 = range(0, 15)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "range(0, 15)\n"
     ]
    }
   ],
   "source": [
    "print(array1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "range"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "type(array1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 1, 8, 27, 64, 125, 216, 343, 512, 729, 1000, 1331, 1728, 2197, 2744]"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Aplicando list comprehension. Dentro da lista aplicando COMANDOS\n",
    "# Para cada item dentro deste array, elevar o elemento ao cubo \n",
    "[item ** 3 for item in array1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 2, 4, 6, 8, 10, 12, 14]"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Retornar apenas os elementos do array que são pares\n",
    "[item for item in array1 if item % 2 == 0]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 4, 16, 36, 64, 100, 144, 196]"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Retornar apenas os elementos do array que elevados ao quadrado serão pares\n",
    "[item ** 2 for item in array1 if item % 2 == 0]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Criar lista de frases\n",
    "lista_frases = [\"Big Data\", \n",
    "                \"Machine Learning em Big Data e Algoritmos em Big Data\", \n",
    "                \"Data Science e Big Data\", \n",
    "                \"Big Data e Internet das Coisas\",\n",
    "                \"Big Data está revolucionando o mundo, pois Big Data é um grande volume de dados\"]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['Machine Learning em Big Data e Algoritmos em Big Data',\n",
       " 'Big Data está revolucionando o mundo, pois Big Data é um grande volume de dados']"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Para cada elementos na lista_frases, retornar apenas as frases que contenham pelo menos dois \"Big Data\"\n",
    "[item for item in lista_frases if item.count(\"Big Data\") >= 2]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0.0,\n",
       " 1.0,\n",
       " 2.0,\n",
       " 3.0,\n",
       " 4.0,\n",
       " 5.0,\n",
       " 6.0,\n",
       " 7.0,\n",
       " 8.0,\n",
       " 9.0,\n",
       " 10.0,\n",
       " 11.0,\n",
       " 12.0,\n",
       " 13.0,\n",
       " 14.0]"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Para cada item no array1, aplicar a função float\n",
    "[float(item) for item in array1]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Funções Lambda"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Funções lambda são funções anônimas que não precisam ser definidas antes de serem usadas. São também chamadas funções inline e ajudam a manter seu código mais organizado."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Definindo um array com a função bulti-in range()\n",
    "array1 = range(0, 15)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "range(0, 15)\n"
     ]
    }
   ],
   "source": [
    "print(array1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "range"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "type(array1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196]"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Aplicando list comprehension\n",
    "[item ** 2 for item in array1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Definindo um função já definida\n",
    "def square(num):\n",
    "    return num ** 2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196]"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Aplicando a função map()\n",
    "list(map(square, array1)) #list para visualizar a função map"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196]"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Função lambda\n",
    "list(map(lambda num: num**2, array1)) "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[4, 16, 36, 64, 100, 144, 196, 256, 324]"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "list(map(lambda a: a**2, filter(lambda a: a % 2 == 0, range(1,20))))"
   ]
  }
 ],
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