S3方法帮助（roxygen2）

我正在尝试在包中使用 S3 方法，并认为在此处提出问题后我明白了如何设置它：使用 Roxygen 构建 R 包时 S3 方法一致性警告 https://stackoverflow.com/questions/14237018/s3-method-consistency

但现在我得到了我意想不到的结果。如果我直接在 R 中运行下面的代码，它会给出预期的结果，但如果我将其编译到包中，我不会得到正确的结果（注意单词 the 被计数两次，而它应该只采用来自的唯一单词）vector a）。我不确定我设置不正确。

.R 文件：

#' Find Common Words Between Groups
#' 
#' Find common words between grouping variables (e.g. people).
#' 
#' @param word.list A list of names chacter vectors.
#' @param overlap Minimum/exact amount of overlap.
#' @param equal.or A character vector of c(\code{"equal"}, \code{"greater"}, 
#' \code{"more"}, \code{"less"}).
#' @param \dots In liu of word.list the user may input n number of character 
#' vectors.
#' @rdname common
#' @return Returns a dataframe of all words that match the criteria set by 
#' \code{overlap} and \code{equal.or}.
#' @export
#' @examples
#' \dontrun{
#' a <- c("a", "cat", "dog", "the", "the")                                                              
#' b <- c("corn", "a", "chicken", "the")                                                                
#' d <- c("house", "feed", "a", "the", "chicken")                                                       
#' common(a, b, d, overlap=2)  
#' common(a, b, d, overlap=3)                                                                          
#'                                                                                                      
#' r <- list(a, b, d)  
#' common(r)                                                                                 
#' common(r, overlap=2)                                                                                            
#'                                                                                                     
#' common(word_list(DATA$state, DATA$person)$cwl, overlap = 2) 
#' } 
common <-
function(word.list, ...){
    UseMethod("common")
}

#' @return \code{NULL}
#'
#' @rdname common
#' @method common list
common.list <-
function(word.list, overlap = "all", equal.or = "more", ...){
    if(overlap=="all") {
        OL <- length(word.list) 
    } else {
        OL <- overlap
    }
    LIS <- sapply(word.list, unique)
    DF <- as.data.frame(table(unlist(LIS)), stringsAsFactors = FALSE)
    names(DF) <- c("word", "freq")
    DF <- DF[order(-DF$freq, DF$word), ]
    DF <- switch(equal.or,
        equal = DF[DF$freq == OL, ],
        greater = DF[DF$freq > (OL - 1), ],
        more = DF[DF$freq > (OL - 1), ],
        less = DF[DF$freq < (OL + 1), ])
    rownames(DF) <- 1:nrow(DF)
    return(DF)
}

#' @return \code{NULL}
#'
#' @rdname common
#' @method common default
#' @S3method common default  
common.default <-
    function(..., overlap = "all", equal.or = "more", word.list){
        LIS <- list(...)
        return(common.list(LIS, overlap, equal.or))
}


a <- c("a", "cat", "dog", "the", "the")                                                              
b <- c("corn", "a", "chicken", "the")                                                                
d <- c("house", "feed", "a", "the", "chicken")                                                       
common(a, b, d, overlap=2)  


r <- list(a, b, d)                                                                                   
common(r, overlap=2)                                                                                            

从命令行运行代码（预期行为）：

> common(a, b, d, overlap=2)  
     word freq
1       a    3
2     the    3
3 chicken    2
>                                                                           
>                                                                                                      
> r <- list(a, b, d)                                                                                   
> common(r, overlap=2)                                                                                            
     word freq
1       a    3
2     the    3
3 chicken    2

包编译后输出：

> a <- c("a", "cat", "dog", "the", "the")                                                              
> b <- c("corn", "a", "chicken", "the")                                                                
> d <- c("house", "feed", "a", "the", "chicken")                                                       
> common(a, b, d, overlap=2)  
     word freq
1       a    3
2     the    3
3 chicken    2
>                                                                           
>                                                                                                      
> r <- list(a, b, d)                                                                                   
> common(r, overlap=2)                                                                                            
     word freq
1     the    4
2       a    3
3 chicken    2

您看到的错误很可能是由于通用泛型的列表方法未导出而引起的，因此common.default而是被调用。您可以使用以下方法解决此问题devtools::missing_s3- 该函数有点启发式，因此您可能会得到一些误报（例如，它当前无法判断is.list不是一种方法）。这是一个非常常见的问题（我已经遇到过很多次了），roxygen 的下一次迭代将采取更多措施来防止它。

目前，要使用 roxygen 正确导出 S3 方法，您需要执行以下任一操作：

• @S3method generic class（仅此而已）如果您不想记录该方法
• @method generic class and @export如果您想导出并记录它。

你不应该有@S3method and @method在同一个文档块中。

roxygen2 更新 >3.0.0

现在，roxygen 会自动判断某个函数是否是 S3 方法，因此：

• 切勿使用@S3method or @method
• Use @export如果您希望导出该方法（您通常会这样做，即使泛型不是）