重复测量 data.frame 和 ggplot

Question

对不起，如果这个问题对大多数人来说可能是超级愚蠢的，但我这周刚开始玩 R。 我正在尝试构建一个 data.frame，其阈值已为每个主题收集了多次（7 个不同的时间点）。 到目前为止，这就是我组织数据的方式：

library(ggplot2)

Subject <- c("1", "1", "1", "1", "1", "1", "1", "1", 
             "2","2","2","2","2","2","2","2",
             "3","3","3","3","3","3","3","3",
             "4","4","4","4","4","4","4","4")

Time <- rep(c(0,1,2,3,4,5,6,7), each = 7) 

Threshold <- c(-17, -24,    -27,    -40,    -25,    -23,    -37,    -40,
               -11, -12,    -11,    0,  -4, -7, -7, -4,
               -1,  -24,    -38,    -34,    -29,    -14,    -21,    -16,
               18,  -10,    -21,    -10,    -5, -17,    -3, -11)

Group <- c("Active","Active","Active","Active","Active","Active","Active","Active",            "Active","Active","Active","Active","Active","Active","Active","Active",           "Control","Control","Control","Control","Control","Control","Control","Control",
"sham","sham","sham","sham","sham","sham","sham","sham")

据我了解，这是必须如何安排数据以进行重复测量（长格式），但现在的问题是：例如，如何为一个特定主题选择一列？假设我想创建一个向量，其中包含第 1 天所有受试者的阈值的平均值。

此外，我如何绘制所有单个数据以及一些 (Mean, Median) 叠加到 geom_point() 图表？

非常感谢。

Answer 1

使用 dplyr 库计算均值的数据框，然后绘制点和均值。

library(ggplot2)
library(dplyr)

Subject <- c("1", "1", "1", "1", "1", "1", "1", "1", 
             "2","2","2","2","2","2","2","2",
             "3","3","3","3","3","3","3","3",
             "4","4","4","4","4","4","4","4")

Time <- rep(c(0,1,2,3,4,5,6,7), each = 4) 

Threshold <- c(-17, -24,    -27,    -40,    -25,    -23,    -37,    -40,
               -11, -12,    -11,    0,  -4, -7, -7, -4,
               -1,  -24,    -38,    -34,    -29,    -14,    -21,    -16,
               18,  -10,    -21,    -10,    -5, -17,    -3, -11)

Group <- c("Active","Active","Active","Active","Active","Active","Active","Active",
           "Active","Active","Active","Active","Active","Active","Active","Active",
           "Control","Control","Control","Control","Control","Control","Control","Control",
           "sham","sham","sham","sham","sham","sham","sham","sham")

# data frame of raw data
df <- data.frame(Subject, Time, Threshold, Group)

# data frame of means
df_means <- group_by(df, Subject) %>% summarize(MeanThresh = mean(Threshold))

ggplot(df, aes(x = Subject, y = Threshold, color = Group)) + 
  geom_point() +
  geom_point(data = df_means, aes(y = MeanThresh), size = 3, color = "black")

一般来说，dplyr 将允许您执行任何您可能想要执行的数据过滤或其他操作，因此我建议您仔细阅读它。