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Both stop and PoisonPill will terminate the actor and stop the message queue. They will cause the actor to cease processing messages, send a stop call 阅读全文
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Apply a Function over a List or Vector Description lapply returns a list of the same length as X, each element of which is the result of applying FUN 阅读全文
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在R语言中,缺失值用 NA 表示,空值用 NULL 表示。初学者在学习R语言时,一般都会被这两者弄糊涂,常常错误地把这两者视为等价的。 下面,通过代码演示来说明它们的不同: 首先看 NA : x <- vector(length=3); x [1] FALSE FALSE FALSE FALSE F 阅读全文
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httr quickstart guide The goal of this document is to get you up and running with httr as quickly as possible. httr is designed to map closely to the 阅读全文