Question

我遇到一个奇怪的问题，如果在另一个函数中使用该函数，data.table函数不能识别明确定义的参数。

这是一个简单的例子：第一个函数testFun1，

时出错

Error in fun(value) : could not find function "fun"

但是，很明显默认值为fun。使用reshape2::dcast没有问题，请参阅testFun2。

testFun1 <- function(data, formula, fun = sum, value.var = "value") {
  data.table::dcast(data = data, formula = formula, fun.aggregate = fun,
                    value.var = "value")
}

testFun2 <- function(data, formula, fun = sum, value.var = "value") {
  reshape2::dcast(data = data, formula = formula, fun.aggregate = fun,
                    value.var = "value")
}

d <- data.table(x = c("a", "b"), y = c("c", "d"), value = 1)
testFun1(d, x ~ y)
# Error in fun(value) : could not find function "fun"
testFun2(d, x ~ y)

Answer 1

这似乎是先前版本的data.table中存在的一个错误，已修复，并再次弹出。

解决方案是将包装函数中的参数名称从fun更改为fun.aggregate，以使其与data.table::dcast参数的名称匹配。

示例：

testFun1 <- function(data, formula, fun.aggregate = sum, value.var = "value") {
  data.table::dcast(data = data, formula = formula, 
                    fun.aggregate = fun.aggregate, value.var = "value")
}

Answer 2

Arun对dcast的最新改进已经解决了该问题。它们很快将以1.12.2版本在CRAN上可用。

install.packages("data.table", repos="https://Rdatatable.gitlab.io/data.table")
library(data.table)
testFun1 <- function(data, formula, fun = sum, value.var = "value") {
  data.table::dcast(data = data, formula = formula, fun.aggregate = fun,
                    value.var = "value")
}

d <- data.table(x = c("a", "b"), y = c("c", "d"), value = 1)
testFun1(d, x ~ y)testFun1 <- function(data, formula, fun = sum, value.var = "value") {
  data.table::dcast(data = data, formula = formula, fun.aggregate = fun,
                    value.var = "value")
}

testFun2 <- function(data, formula, fun = sum, value.var = "value") {
  reshape2::dcast(data = data, formula = formula, fun.aggregate = fun,
                  value.var = "value")
}

d <- data.table(x = c("a", "b"), y = c("c", "d"), value = 1)
all.equal(testFun1(d, x ~ y), as.data.table(testFun2(d, x ~ y)), check.attributes=FALSE)
#[1] TRUE

R data.table函数不识别已经指定的参数

2 个答案: