从长到宽整形并创建具有二进制值的列 [英] Reshape from long to wide and create columns with binary value

问题描述

我知道 tidyr 包中的价差函数，但这是我无法实现的。
我有一个 data.frame ，其中有2列，定义如下。我需要将列 Subject 转换为具有1和0的二进制列。

I am aware of the spread function in the tidyr package but this is something I am unable to achieve. I have a data.frame with 2 columns as defined below. I need to transpose the column Subject into binary columns with 1 and 0.

下面是数据框：

studentInfo <- data.frame(StudentID = c(1,1,1,2,3,3),
         Subject = c("Maths", "Science", "English", "Maths", "History", "History"))

> studentInfo
  StudentID Subject
1         1   Maths
2         1 Science
3         1 English
4         2   Maths
5         3 History
6         3 History

我期望的输出是：

  StudentID Maths Science English History
1         1     1       1       1       0
2         2     1       0       0       0
3         3     0       0       0       1

如何使用 spread（）函数或任何其他方法执行此操作

How can I do this with the spread() function or any other function.

推荐答案

使用 reshape2 我们可以 dcast 从长到宽。

Using reshape2 we can dcast from long to wide.

由于只需要二进制结果，我们可以唯一数据优先

As you only want a binary outcome we can unique the data first

library(reshape2)

si <- unique(studentInfo)
dcast(si, formula = StudentID ~ Subject, fun.aggregate = length)

#  StudentID English History Maths Science
#1         1       1       0     1       1
#2         2       0       0     1       0
#3         3       0       1     0       0

---

另一种使用 tidyr 和 dplyr的方法是

library(tidyr)
library(dplyr)

studentInfo %>%
  mutate(yesno = 1) %>%
  distinct %>%
  spread(Subject, yesno, fill = 0)

#  StudentID English History Maths Science
#1         1       1       0     1       1
#2         2       0       0     1       0
#3         3       0       1     0       0

尽管我还不是 tidyr 语法的粉丝...

Although I'm not a fan (yet) of tidyr syntax...

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