September 2025
Intermediate to advanced
660 pages
13h 38m
Portuguese (Portugal, Brazil)
Content preview from Introdução ao Python, 3rd Edition
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Capítulo 9. Dicionários e conjuntos
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Se uma palavra do dicionário estivesse escrita incorretamente, como você saberia?
Steven Wright
Os dicionários são estruturas de dados de chave-valor particularmente úteis e você os verá usados em todos os lugares em Python. Os conjuntos são apenas sacos de chaves exclusivas e geralmente são muito úteis.
Dicionários
Um dicionário é semelhante a uma lista, mas a ordem dos itens não importa e eles não são selecionados por um deslocamento, como 0 ou 1. Em vez disso, você especifica uma chave exclusiva para associar a cada valor. Essa chave geralmente é uma cadeia de caracteres, mas pode ser qualquer um dos tipos imutáveis do Python: booleano, inteiro, float, tupla, cadeia de caracteres e outros - até mesmo os que você definiu. Os dicionários são mutáveis, portanto, você pode adicionar, excluir e alterar os elementos chave-valor. Se você já trabalhou com linguagens que suportam apenas matrizes ou listas, vai adoraros dicionários.
Observação
Em outras linguagens, os dicionários podem ser chamados dematrizes associativas, hashes ou hashmaps. Em Python, um dicionário também é chamado de dictpara economizar sílabas e fazer os adolescentes rirem.
Criar com {}
Para criar um dicionário, você coloca chaves ({}) ao redor de campos separados por vírgulas key :value O dicionário mais simples é vazio e não contém chaves ou valores:
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