如何将变量的行转换为出现和 grouped_by 的列？

Question

我有一个看起来像这样的数据集

Group| School
11-12  Middle School
8-10   Elementary 
5-8    Elementary
5-8    Elementary
8-10   Elementary
14-16  High School
11-13  Middle School

如何把它变成

 Group|Elementary|Middle School|High School
 5-8            2             0          0
 8-10           2             0          0
11-12           0             1          0
11-13           0             1          0
14-16           0             0          1

Answer 1

我们可以使用 base R 中的 table，它给出 matrix/table class

中的频率 table

table(df1)

或者如果我们需要一个 tidyverse 选项

library(dplyr)
library(tidyr)
df1 %>%
  pivot_wider(names_from = 'School', 
    values_from = 'School', values_fn = length, values_fill = 0)

或 dcast 来自 data.table

library(data.table)
dcast(setDT(df1), Group ~ School, fun.aggregate = length, fill = 0)

如何将变量的行转换为出现和 grouped_by 的列？

How to turn rows of a variable into columns with occurrence and grouped_by?

pivot

group-by

r

dplyr