按多列聚合并从长到宽重塑

问题描述

在 SO 上有一些与此主题类似的问题，但与我的用例并不完全相同.我有一个数据集，其中列的布局如下所示

There are some questions similar to this topic on SO but not exactly like my usecase. I have a dataset where the columns are laid out as shown below

     Id        Description          Value
     10        Cat                  19
     10        Cat                  20
     10        Cat                  5
     10        Cat                  13
     11        Cat                  17
     11        Cat                  23
     11        Cat                  7
     11        Cat                  14
     10        Dog                  19
     10        Dog                  20
     10        Dog                  5
     10        Dog                  13
     11        Dog                  17
     11        Dog                  23
     11        Dog                  7
     11        Dog                  14

我想要做的是通过 Id、Description 捕获 Value 列的平均值.最终的数据集看起来像这样.

What I am trying to do is capture the mean of the Value column by Id, Description. The final dataset would look like this.

     Id       Cat         Dog
     10       14.25       28.5
     11       15.25       15.25

我可以用非常粗略的方式来做到这一点，像这样效率不高

I can do this in a very rough manner not very efficient like this

tempdf1 <- df %>%
  filter(str_detect(Description, "Cat")) %>%
   group_by(Id, Description) %>%
  summarize(Mean_Value = mean(Value) , na.rm = TRUE))

这不是很方便.任何关于如何更有效地实现预期结果的建议都非常感谢.

This is not very convenient. Any advise on how how to accomplish the expected results more efficiently is much appreciated.

推荐答案

使用 dcast 甚至 acast 来自 reshape2() 包>

Use dcast or even acast from reshape2() package

dcast(dat,Id~Description,mean)
   Id   Cat   Dog
 1 10 14.25 14.25
 2 11 15.25 15.25

Base R 可能有点长:

 reshape(aggregate(.~Id+Description,dat,mean),direction = "wide",v.names  = "Value",idvar = "Id",timevar = "Description")
  Id Value.Cat Value.Dog
1 10     14.25     14.25
2 11     15.25     15.25

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