如何覆盖包名称空间中的不可见函数? [英] How do I override a non-visible function in the package namespace?
问题描述
我基本上想要改变一个包的不可见功能。对于可见的函数,即在调用方法
时没有asterix的函数,我发现了两篇文章,可以实现我的目标:
- 使用
assignInNamespace
:参见 R-help 。 使用修正
:请参阅 stackoverflow
尽管这两种方法都适用于导出/可见函数(我使用 predict.lm
作为第二种方法的进一步示例,并且使用函数 subset.data.frame
)测试了第一种方法,但它们不适用于不可见函数,例如 predict.ar
。这是为什么?是否有解决方法?
以下是一个简单示例:
显示predict.lm可见,预测.ar不是:
方法(预测)
[1]预测.Arima *预测.HoltWinters *预测。 StructTS *
[4] predict.ar * predict.arima0 * predict.glm
[7] predict.lm predict.loess * predict.mlm
[10] predict.nls * predict。 poly predict.ppr *
[13] predict.prcomp * predict.princomp * predict.smooth.spline *
[16] predict.smooth.spline.fit *
应用 predict.lm
:
x < - rnorm(5)
y <-x + rnorm(5)
predict(lm(y〜x))
#1 2 3 4 5
#1.0783047 1.5288031 0.3268405 0.8373520 -0.9833746
更改 predict.lm
,方法是在函数体的开头输入cat(first line changed for predict.lm \\\
)
。 (您必须在编辑器中手动执行此操作):
fix(predict.lm)
predict(lm( y〜x))
#预测的第一行已更改
#1 2 3 4 5
#1.0783047 1.5288031 0.3268405 0.8373520 -0.983374
应用 predict.ar
:
<$ p (太阳黑子年)
预测(太阳黑子,n.ahead = 25)
#$ pred
#时间系列:
#开始= 1989
#结束= 2013
尝试更改 predict.ar
:
fix(predict.ar)#这里,一个空的函数体出现给我
fix(stats ::: predict.ar)#这里还有
fix(stats ::: predict.ar)
# stats ::: predict.ar):'fix'需要一个名字
尝试使用 assignInNamespace
代替。 (请注意,我只是在编辑器中复制了函数 stats ::: predict.ar
并添加了 cat这行(第一行已更改为预测。 ar \ n)
,因为函数体很长,所以我只显示前几行)
mypredict< - 函数(object,newdata,n.ahead = 1,se.fit = TRUE,...)
{
cat(如果(n.ahead <1)
stop(n.ahead必须至少为1),
#Rest变为predict.ar\
的第一行)
统计信息::: predict.ar
}
assignInNamespace(predict.ar,mypredict,ns =stats)
predict(sunspot.ar,n.ahead = 25 )
#预测的第一行改变
#预测的错误(sunspot.ar,n.ahead = 25):
#object'C_artoma'找不到
由于predict.ar的第一行更改实际上已打印到控制台,因此predict.ar必须已更改。然而,为什么没有找到对象'C_artoma'?
更新:好吧,这太令人尴尬了,但我不能删除该帖子:答案是已经在我最后提供Richie Cotton答案的链接上。对不起浪费你的时间!我想我查了一切,然后我没有看到明显的。有人可以发布这个答案,我接受它。
fixInNamespace(predict.ar,pos =package:stats)
fixInNamespace
。 :) fixInNamespace(predict.ar,stats)
或
fixInNamespace(predict.ar, pos =package:stats)
几年后......)
来自Nicholas H的评论:如果你想将一些代码推送到依赖于来自另一个包的内部函数的CRAN,它将抛出一个构建警告并被R核拒绝。如果你需要这个内部函数,你应该使用 :::
操作符来拷贝它,并自己维护它。
predict.ar< - stats ::: predict.ar
I basically want to change a non-visible function of a package. For visible functions, i.e. functions that have no asterix when methods
is called on them, I found two posts how I could achieve my goal:
- Use
assignInNamespace
: see post on R-help. - Use
fix
: see post on stackoverflow
Although both approaches work for an exported / visible function (I use predict.lm
as an example further below for the second approach and tested the first approach with the function subset.data.frame
), they do not work for a non-visible function, e.g. predict.ar
. Why is that? Is there a workaround?
Here is a minimal example:
Show that predict.lm is visible, predict.ar is not:
methods(predict)
[1] predict.Arima* predict.HoltWinters* predict.StructTS*
[4] predict.ar* predict.arima0* predict.glm
[7] predict.lm predict.loess* predict.mlm
[10] predict.nls* predict.poly predict.ppr*
[13] predict.prcomp* predict.princomp* predict.smooth.spline*
[16] predict.smooth.spline.fit*
Apply predict.lm
:
x <- rnorm(5)
y <- x + rnorm(5)
predict(lm(y ~ x))
# 1 2 3 4 5
# 1.0783047 1.5288031 0.3268405 0.8373520 -0.9833746
Change predict.lm
by entering cat("First line changed for predict.lm\n")
at the beginning of the function body. (You have to do that manually in the editor):
fix(predict.lm)
predict(lm(y ~ x))
# First line changed for predict.lm
# 1 2 3 4 5
# 1.0783047 1.5288031 0.3268405 0.8373520 -0.983374
Apply predict.ar
:
sunspot.ar <- ar(sunspot.year)
predict(sunspot.ar, n.ahead=25)
# $pred
# Time Series:
# Start = 1989
# End = 2013
Try to change predict.ar
:
fix(predict.ar) #Here, an empty function body appears for me
fix("stats:::predict.ar") #Here as well
fix(stats:::predict.ar)
#Error in fix(stats:::predict.ar) : 'fix' requires a name
Try to use assignInNamespace
instead. (Note that I just copied the function stats:::predict.ar
in an editor and added the line cat("First line changed for predict.ar\n")
at the beginning of the body. Because the function body is quite long, I only show the first couple of lines here)
mypredict <- function (object, newdata, n.ahead = 1, se.fit = TRUE, ...)
{
cat("First line changed for predict.ar\n")
if (n.ahead < 1)
stop("'n.ahead' must be at least 1")
#Rest of body of stats:::predict.ar
}
assignInNamespace("predict.ar", mypredict, ns="stats")
predict(sunspot.ar, n.ahead=25)
# First line changed for predict.ar
# Error in predict.ar(sunspot.ar, n.ahead = 25) :
# object 'C_artoma' not found
Since "First line changed for predict.ar" is actually printed to the console, predict.ar must have been changed. However, why is the object 'C_artoma' not found anymore?
UPDATE: OK, this is super embarrassing, but I can't delete that post anymore: The answer was already at the link I provided with Richie Cotton's answer at the end. Sorry for wasting your time! I think I checked everything and then I don't see the obvious. Could someone just post this as an answer an I accept it. Sorry again.
fixInNamespace(predict.ar, pos="package:stats")
Use fixInNamespace
. :)
fixInNamespace("predict.ar", "stats")
or
fixInNamespace("predict.ar", pos="package:stats")
(Several years later...)
From Nicholas H's comment: if you want to push some code to CRAN that depends upon an internal function from another package, it will throw a build warning and be rejected by R-core. If you want that internal function, you should just take a copy of it using the :::
operator and maintain it yourself.
predict.ar <- stats:::predict.ar
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