dplyr使用汇总时仅返回一行 [英] dplyr only returning one row when using summarize

问题描述

我只是想尝试一下dplyr的连锁经营者。

I'm just getting around to giving dplyr's chain operator a try.

使用简单示例：

group_by(mtcars, cyl) %>%
summarise(mean(disp), mean(hp))

I得到结果：

  # mean(disp) mean(hp)
  #1   230.7219 146.6875

出于某些原因，dplyr并未分组，只是汇总了整个向量。我缺少什么？

For some reason dplyr isn't grouping, just summarizing the entire vector. What am I missing?

推荐答案

开始一个新的会话，这是我得到的：

Start a fresh session this is what I get:

library(dplyr)

mtcars %>%
    group_by(cyl) %>%
    summarise(mean(disp), mean(hp))

##   cyl mean(disp)  mean(hp)
## 1   4   105.1364  82.63636
## 2   6   183.3143 122.28571
## 3   8   353.1000 209.21429

编辑

Don' t每秒加载 plyr （仅次于 dplyr ）。问题在于它使用的是 plyr :: summarise 而不是 dplyr :: summarise ：

Don't load plyr second (after dplyr) or at all. The problem is that it's using plyr::summarise not dplyr::summarise:

mtcars %>%
    group_by(cyl) %>%
    plyr::summarise(mean(disp), mean(hp))

##   mean(disp) mean(hp)
## 1   230.7219 146.6875

编辑2

您也可以明确地说出要从哪个包中提取 sumamrise 的软件包，如下所示：

You could also just be explicit and say which package to pull sumamrise from as seen below:

mtcars %>%
    group_by(cyl) %>%
    dplyr::summarise(mean(disp), mean(hp))

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