r - 使用二进制值时 R 中的直方图

Question

我有几所学校的学生数据。我想使用 R 显示每所学校通过测试的所有学生百分比的直方图。我的数据如下所示（id、学校、通过/失败）：

432342 school1 通过

454233 school2 失败

543245 school1 失败

ETC'

（重点是我只对通过的学生百分比感兴趣，显然那些没有通过的学生不及格。我希望每所学校都有一个栏目，显示该学校通过的学生百分比）

谢谢

Answer 1

有很多方法可以做到这一点。一个是：

df<-data.frame(ID=sample(100),
school=factor(sample(3,100,TRUE),labels=c("School1","School2","School3")),
result=factor(sample(2,100,TRUE),labels=c("passed","failed")))

p<-aggregate(df$result=="passed"~school, mean, data=df)
barplot(p[,2]*100,names.arg=p[,1])

Answer 2

我之前的回答并没有完全成功。这是重做。示例是来自@eyjo 的答案。

students <- 400
schools <- 5

df <- data.frame(
  id = 1:students,
  school = sample(paste("school", 1:schools, sep = ""), size = students, replace = TRUE),
  results = sample(c("passed", "failed"), size = students, replace = TRUE, prob = c(.8, .2)))

r <- aggregate(results ~ school, FUN = table, data = df)
r <- do.call(cbind, r) # "flatten" the result
r <- as.data.frame(cbind(r, sum = rowSums(r)))

r$perc.passed <- round(with(r, (passed/sum) * 100), 0)

library(ggplot2)

ggplot(r, aes(x = school, y = perc.passed)) +
  theme_bw() +
  geom_bar(stat = "identity")

Answer 3

由于您有个人记录（id）并且想根据索引（学校）进行计算，我建议tapply这样做。

students <- 400
schools <- 5

df <- data.frame("id" = 1:students,
    "school" = sample(paste("school", 1:schools, sep = ""),
        size = students, replace = TRUE),
    "results" = sample(c("passed", "failed"),
        size = students, replace = TRUE, prob = c(.8, .2)))

p <- tapply(df$results == "passed", df$school, mean) * 100

barplot(p)