％函数之间的％可能改善 [英] %between% function possible improvement

问题描述

根据 data.table ver 1.8.8 ％between％之间的定义如下：

 > `％between％`
函数（x，y）
在（x，y [1]，y [2]，incbounds = TRUE之间）
< bytecode：0x0000000050912810& 
< environment：namespace：data.table> 
  

我认为，这个微小的变化，这个函数会被矢量化，

$ b （x，y [[1]]，y [[2]]，incbounds = TRUE）之间的函数（x，y）
$ b <$ c $ p>

像之间

  s <-c（2,5）
d <-c（7,9）
& （3，s，d）
 [1] TRUE FALSE 
  

具有两个向量的列表，其建议我这种可能的用法：

 `between2％`< ）between（x，lst [[1]]，lst [[2]]，incbounds = TRUE）
 
> ％c（s，d）之间的3％
 [1] TRUE 
> 3％between2％list（s，d）
 [1] TRUE FALSE 
  

是：如果我替换％之间的％会影响 data.table 包中的任何功能？我认为它不应该， [[应该使用原子向量 [。我对么？感谢

 > 3％between2％c（1,5）
 [1] TRUE 
  

解决方案

我认为这是一个有趣的问题，因为我想知道一个人可能看起来，一般来说，对其他函数的函数的使用。据我所知，没有办法直接这样做（也许有人可以纠正我？）。但是，我把一些小的代码，在其他函数的文本表示中查找函数名称。 ％between％之间，如下：

  table）
 objs<  -  objects（package：data.table）
z<  -  textConnection（funs，open =w）
 dump（list = objs，file = b）
 close（z）
 
＃在数据表中查找％between之间的所有提及函数
 funs [grep（％between％ ] ##只提到％之间的％定义
 
＃查找`data.table`中所有`data.table`函数的所有提及函数
 locations<  -  lapply （objs，function（x）grep（x，funs））
 names（locations）< -  objs 
  

UPDATE ：在进行更多搜索后， this question / answer 似乎还提供了一些关于如何使用 foodweb 从库（mvbutils） / code>。

As per data.table ver 1.8.8 %between% is defined as follow:

> `%between%`
function (x, y) 
between(x, y[1], y[2], incbounds = TRUE)
<bytecode: 0x0000000050912810>
<environment: namespace:data.table>

I thought that, with this tiny change, this function would be vectorised,

function (x, y) 
    between(x, y[[1]], y[[2]], incbounds = TRUE)

like between

s <- c(2, 5)
d <- c(7, 9)
> between(3, s, d)
[1]  TRUE FALSE

The idea came from having a list with two vectors, which suggested me this possible usage:

`between2%` <- function(x, lst) between(x, lst[[1]], lst[[2]], incbounds = TRUE)

> 3%between%c(s,d)
[1] TRUE
> 3%between2%list(s,d)
[1]  TRUE FALSE

My question is: if I replaced %between% would any functionality in data.table package be affected? I think it shouldn't, [[ should work with atomic vector as [ does. Am I correct? thanks

> 3%between2%c(1,5)
[1] TRUE

解决方案

I thought this was an interesting question because I wondered how one might look, in general, for uses of a function by other functions. As far as I know, there's no way to directly do this (perhaps someone can correct me?). But, I put together a little code that looks for function names in text representations of other functions. For %between%, here's the following:

library(data.table)
objs <- objects("package:data.table")
z <- textConnection("funs", open="w")
dump(list=objs, file=z)
close(z)

# find all mentions of `%between%` in `data.table` functions
funs[grep("%between%",funs)] ## only mentions are when %between% is defined

# find all mentions of all `data.table` functions in `data.table` functions
locations <- lapply(objs, function(x) grep(x,funs))
names(locations) <- objs

UPDATE: After doing some more searching, this question/answer also seem to provide some more information on how to detect dependencies programmatically using foodweb from library(mvbutils).

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