April 2025
Intermediate to advanced
578 pages
13h 35m
Portuguese (Portugal, Brazil)
library(tidyverse)
Content preview from R for Data Science, 2ª Edição
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Capítulo 16. Factores
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Introdução
Os factores são utilizados para variáveis categóricas, variáveis que têm um conjunto fixo e conhecido de valores possíveis. Também são úteis quando pretendes apresentar vectores de caracteres numa ordem não alfabética.
Começaremos por explicar porque é que os factores são necessários para a análise de dados1 e como podes criá-los com factor(). Em seguida, apresentaremos o conjunto de dados gss_cat, que contém um monte de variáveis categóricas para experimentar. Em seguida, utilizarás esse conjunto de dados para praticar a modificação da ordem e dos valores dos factores, antes de terminarmos com uma discussão sobre factores ordenados.
Pré-requisitos
A base R fornece algumas ferramentas básicas para criar e manipular factores. Vamos complementá-las com o pacote forcats, que faz parte do núcleo do tidyverse. Fornece ferramentas para lidar com variáveis categóricas(e é um anagrama de factores!) utilizando uma vasta gama de auxiliares para trabalhar com factores.
Noções básicas sobre factores
Imagina que tens uma variável que regista o mês:
x1<-c("Dec","Apr","Jan","Mar")
A utilização de uma cadeia de caracteres para registar esta variável tem dois problemas:
-
Só há 12 meses possíveis e não há nada que te salve de erros de digitação:
x2<-c("Dec","Apr","Jam","Mar") -
Não classifica de uma forma ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.