在ggplot2中为两个地点()更改颜色。

Sample dataset:

样本数据集:

library(ggplot2)    
df = read.table(text = 
              "id      year    value1  value2 value3
            1           2000    1   2000      2001
            1           2001    2   NA        NA
            1           2002    2   2000      NA
            1           2003    2   NA         2003
            2           2000    1   2001     2003
            2           2002    2   NA       2000
            2           2003    3   2002     NA
            3           2002    2   2001     NA
        ", sep = "", header = TRUE)
df$value1 <- as.factor(df$value1)
library(ggplot2)