magrittr中％&％;％和％，％之间有什么区别? [英] What is the difference between %>% and %,% in magrittr?

问题描述

magrittr的Github开发版本包括一些很酷的管道新功能，但我没有完全了解%>%和%,%之间的区别.这只是形式上带有%>%表示值，%,%表示函数，还是有些特殊之处?

Github developmental version of magrittr includes some cool new function for piping but I do not exactly catch de difference between %>% and %,%. Is this only formal with %>% for value and %,% for functions, or there is some specific peculiarity?

推荐答案

常规管道运算符为%>%.您可以使用%,%创建可重复使用的管道，即没有数据的管道.然后，您可以将同一管道与各种数据集一起使用.这是一个例子.

The normal piping operator is %>%. You can use %,% to create a reusable pipe, a pipe without data. Then later you can use the same pipe with various data sets. Here is an example.

library(magrittr)
library(dplyr)
library(Lahman)

假设您要根据总点击次数来计算排名前5位的棒球运动员.然后，您可以执行以下操作(取自magrittr自述文件):

Suppose you want to calculate the top 5 baseball players, according to total hits. Then you can do something like this (taken from the magrittr README):

Batting %>%
   group_by(playerID) %>%
   summarise(total = sum(G)) %>%
   arrange(desc(total)) %>%
   head(5)
# Source: local data frame [5 x 2]
# 
#    playerID total
# 1  rosepe01  3562
# 2 yastrca01  3308
# 3 aaronha01  3298
# 4 henderi01  3081
# 5  cobbty01  3035

到目前为止，一切都很好.现在，假设您具有与Batting相同格式的多个数据集，因此可以再次使用同一管道. %,%帮助您创建，保存和重复使用管道:

So far so good. Now let's assume that you have several data sets in the same format as Batting, so you could just reuse the same pipe again. %,% helps you create, save and reuse the pipe:

top_total <- group_by(playerID) %,%
   summarise(total = sum(G)) %,%
   arrange(desc(total)) %,%
   head(5)

top_total(Batting)
# Source: local data frame [5 x 2]
# 
#    playerID total
# 1  rosepe01  3562
# 2 yastrca01  3308
# 3 aaronha01  3298
# 4 henderi01  3081
# 5  cobbty01  3035

当然，您也可以使用常规的R方法(即top_total <- function(...) ...)创建函数，但是%,%是更简洁的方法.

Of course you could also create a function the regular R way, i.e. top_total <- function(...) ..., but %,% is a more concise way.

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