使用tidyr spread函数创建具有二进制值的列

Question

我知道包中的spread功能,tidyr但这是我无法实现的.我有一个data.frame有2列,如下所示.我需要将列Subject转换为带有1和0的二进制列.

下面是data.frame

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

我期待的输出是:

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

请使用"传播"功能或任何其他功能协助如何执行此操作.谢谢

Answer 1

使用reshape2我们可以dcast从长到宽.

由于您只需要二进制结果,我们可以先unique获取数据

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

使用tidyr和的另一种方法dplyr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

虽然我不是tidyr语法的粉丝......

Answer 2

我们可以使用table从base R

+(table(studentInfo)!=0)
#            Subject
#StudentID English History Maths Science
 #       1       1       0     1       1
 #       2       0       0     1       0
 #       3       0       1     0       0

Answer 3

使用tidyr：

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

pivot_wider(studentInfo,
            names_from = "Subject", 
            values_from = 'Subject', 
            values_fill = 0,
            values_fn = function(x) 1)
#> # A tibble: 3 x 5
#>   StudentID Maths Science English History
#>       <dbl> <int>   <int>   <int>   <int>
#> 1         1     1       1       1       0
#> 2         2     1       0       0       0
#> 3         3     0       0       0       1

^{由reprex 包(v0.3.0)于 2019 年 9 月 19 日创建}