tapply(base)
tapply()所属R语言包：base
Apply a Function Over a Ragged Array
申请超过一个衣衫褴褛的阵列功能
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Apply a function to each cell of a ragged array, that is to each (non-empty) group of values given by a unique combination of the levels of certain factors.
套用一个衣衫褴褛的数组的每个单元的功能，这是每个值（非空）组的某些因素水平的独特组合。
用法----------Usage----------
tapply(X, INDEX, FUN = NULL, ..., simplify = TRUE)
参数----------Arguments----------
参数：X
an atomic object, typically a vector.
一个原子的对象，通常是一个矢量。
参数：INDEX
list of factors, each of same length as X. The elements are coerced to factors by as.factor.
列表的因素，相同长度的每个X。 as.factor元素被强制因素。
参数：FUN
the function to be applied, or NULL. In the case of functions like +, %*%, etc., the function name must be backquoted or quoted. If FUN is NULL, tapply returns a vector which can be used to subscript the multi-way array tapply normally produces.
要应用的功能，或NULL。在像+，%*%等，函数的名称必须backquoted或引述的职能。如果FUN是NULL，tapply返回一个可以被用于多路数组下标tapply正常生产向量。
参数：...
optional arguments to FUN: the Note section.
FUN可选参数：注节。
参数：simplify
If FALSE, tapply always returns an array of mode "list". If TRUE (the default), then if FUN always returns a scalar, tapply returns an array with the mode of the scalar.
如果FALSE，tapply总是返回一个数组模式"list"。如果TRUE（默认），那么FUN总是返回一个标量，tapply返回数组与标量模式。
值----------Value----------
If FUN is not NULL, it is passed to match.fun, and hence it can be a function or a symbol or character string naming a function.
FUN如果非NULL，它传递给match.fun，因此它可以是一个函数或一个符号或字符的字符串命名函数。
When FUN is present, tapply calls FUN for each cell that has any data in it. If FUN returns a single atomic value for each such cell (e.g., functions mean or var) and when simplify is TRUE, tapply returns a multi-way array containing the values, and NA for the empty cells. The array has the same number of dimensions as INDEX has components; the number of levels in a dimension is the number of levels (nlevels()) in the corresponding component of INDEX. Note that if the return value has a class (e.g. an object of class "Date") the class is discarded.
当FUN目前，tapply要求FUN每个单元中有任何数据。如果FUN返回为每个这样的单元单个原子值（例如，功能mean或var）simplifyTRUE，tapply返回的多路数组包含的值，和NA空单元。数组有相同的维数INDEX组件;维度中的级别数的级别数（nlevels()）在INDEX的相应组件。请注意，如果返回值类（例如，一个类的对象"Date"）类的被丢弃。
Note that contrary to S, simplify = TRUE always returns an array, possibly 1-dimensional.
请注意，相反为S，simplify = TRUE总是返回一个数组，可能是一维的。
If FUN does not return a single atomic value, tapply returns an array of mode list whose components are the values of the individual calls to FUN, i.e., the result is a list with a dim attribute.
如果FUN不返回单个原子值，tapply模式list，其成分是FUN，即在单个呼叫的值返回一个数组，其结果是dim属性列表。
When there is an array answer, its dimnames are named by the names of INDEX and are based on the levels of the grouping factors (possibly after coercion).
当有一个数组的答案，它的dimnames命名由INDEX的名称和基于分组因素水平（可能在胁迫）。
For a list result, the elements corresponding to empty cells are NULL.
对于一个列表的结果，相应的空单元格的元素是NULL。
注意----------Note----------
Optional arguments to FUN supplied by the ... argument are not divided into cells. It is therefore inappropriate for FUN to expect additional arguments with the same length as X.
可选参数FUN...参数提供不分为单元。因此，这是不适当的FUN期待与X相同长度的额外的参数。
参考文献----------References----------
The New S Language. Wadsworth & Brooks/Cole.
参见----------See Also----------
the convenience functions by and aggregate (using tapply); apply, lapply with its versions sapply and mapply.
便利功能by和aggregate（使用tapply）apply，lapply其版本sapply和mapply。
举例----------Examples----------
require(stats)
groups <- as.factor(rbinom(32, n = 5, prob = 0.4))
tapply(groups, groups, length) #- is almost the same as[ - 是几乎一样]
table(groups)
## contingency table from data.frame : array with named dimnames[＃从数据框的应变表：阵列名为dimnames]
tapply(warpbreaks$breaks, warpbreaks[,-1], sum)
tapply(warpbreaks$breaks, warpbreaks[, 3, drop = FALSE], sum)
n <- 17; fac <- factor(rep(1:3, length = n), levels = 1:5)
table(fac)
tapply(1:n, fac, sum)
tapply(1:n, fac, sum, simplify = FALSE)
tapply(1:n, fac, range)
tapply(1:n, fac, quantile)
## example of ... argument: find quarterly means[＃范例......参数：找到每季手段]
tapply(presidents, cycle(presidents), mean, na.rm = TRUE)
ind <- list(c(1, 2, 2), c("A", "A", "B"))
table(ind)
tapply(1:3, ind) #-> the split vector[ - >分裂矢量]
tapply(1:3, ind, sum)
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
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发表于 2012-2-16 18:23:28
