如何使用r访问列中的一些特定类？

Question

我在访问列中的特定类时遇到了问题。我的数据框架如下。

library(ggplot2)
library(dplyr)

dat <- data.frame(
  time = factor(c("Breakfast","Breakfast","Breakfast","Breakfast","Breakfast","Lunch","Lunch","Lunch","Lunch","Lunch","Lunch","Dinner","Dinner","Dinner","Dinner","Dinner","Dinner","Dinner"), levels=c("Breakfast","Lunch","Dinner")),
  class = c("a","a","b","b","c","a","b","b","c","c","c","a","a","b","b","b","c","c"))

在列中 time 我只对检测感兴趣 Breakfast 和 Dinner 为类 a, b 和 c 因此，从该数据框架中，我只想在表格中查看它，它将像这样。

            a    b    c
Breakfast   2    2    1
Dinner      2    3    2

所以对于每个类 a,b,c 我想画两根柱子。例如类 a 一条代表。平均值 Breakfast 与其他班级相比：2(2+2+1)和一个其他的条形代表了 Dinner 与其他类比较：2(2+3+2)，并将它们设置为不同的颜色。我想对班级进行同样的设置 b 和类 c.

任何帮助将非常感激。

Answer 1

我们可以 subset 和 table 丢下 levels 与 droplevels

table(droplevels(subset(dat, time %in% c("Breakfast", "Dinner"))))
#           class
#time        a b c
#  Breakfast 2 2 1
# Dinner    2 3 2

如果我们需要一个 barplot

barplot(prop.table(table(droplevels(subset(dat, time %in% 
            c("Breakfast", "Dinner")))), 1), beside = TRUE)

---

或与 ggplot

library(dplyr)
library(ggplot2)
dat %>% 
   filter(time %in% c("Breakfast", "Dinner")) %>%
   droplevels %>%
   count(time, class) %>% 
   group_by(time) %>% 
   mutate(prop = n/sum(n)) %>%
   ggplot(aes(x = class, y = prop, fill = time, label = scales::percent(prop))) +
   geom_col(position = 'dodge') +
   geom_text(position = position_dodge(width = 0.9), vjust = 0.5, size = 3) + 
   scale_y_continuous(labels = scales::percent)