April 2025
Intermediate to advanced
578 pages
13h 35m
Portuguese (Portugal, Brazil)
Content preview from R for Data Science, 2ª Edição
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Capítulo 17. Datas e horas
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Introdução
Este capítulo vai mostrar-te como trabalhar com datas e horas no R. À primeira vista, as datas e as horas parecem simples. Estás sempre a usá-las na tua vida normal e não parecem causar muita confusão. No entanto, quanto mais aprendes sobre datas e horas, mais complicadas elas se tornam!
Para te aqueceres, pensa no número de dias que há num ano e no número de horas que há num dia. Provavelmente lembras-te que a maioria dos anos tem 365 dias, mas os anos bissextos têm 366. Conheces a regra completa para determinar se um ano é bissexto?1 O número de horas num dia é um pouco menos óbvio: a maioria dos dias tem 24 horas, mas nos locais que utilizam a hora de verão (DST), um dia por ano tem 23 horas e outro tem 25.
As datas e horas são difíceis porque têm de conciliar dois fenómenos físicos (a rotação da Terra e a sua órbita em torno do Sol) com uma série de fenómenos geopolíticos, incluindo meses, fusos horários e horário de verão. Este capítulo não te ensinará todos os pormenores sobre datas e horas, mas dar-te-á uma base sólida de competências práticas que te ajudarão nos desafios comuns da análise de dados.
Começaremos por te mostrar como criar datas-tempo a partir de vários inputs e, depois de obteres uma data-tempo, aprenderás a extrair componentes como o ano, o mês e o dia. Em seguida, vamos mergulhar no tópico complicado ...
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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.