如何根据行创建不同颜色的R散点图？

Question

我在RStudio中导入了以下数据集

我想做一个散点图，其中第1至3行的点是红色，其余行的点是蓝色。我该如何修改代码？

 plot(x=dataset$`col1`,y=dataset$col2, xlab="col1", ylab="col2",pch=16)

Answer 1

如果您对前三行的颜色感到满意，可以使用以下方法：

dataset <- data.frame(col1 = 1:5,
                      col2 = 1,
                      row.names = c("a", "b", "c", "d", "e"))


my_colors <- c(rep("red", 3), # first 3 red
               rep("blue", nrow(dataset) - 3)) # rest is blue
plot(x = dataset$col1,
     y = dataset$col2, 
     xlab = "col1", 
     ylab = "col2",
     pch = 16, 
     col = my_colors)

Answer 2

其他选项

library(tidyverse)
set.seed(0)
df <- tibble(
  col1 = runif(5),
  col2 = runif(5)
  ) %>% 
  mutate(grp = row_number()<= 3)

ggplot(df, aes(col1, col2, color = grp)) +
  geom_point() +
  scale_color_manual(values = c("red", "blue")) +
  theme(legend.position = "none")

Answer 3

通常，您可以先初始化一个空的plot，然后在具有所需颜色的相应子集上初始化points。

with(dataset, plot(col1, col2, xlab="col1", ylab="col2", type="n"))
with(dataset[1:3, ], points(col1, col2, pch=16, col="red"))
with(dataset[-(1:3), ], points(col1, col2, pch=16, col="blue"))

---

数据

dataset <- structure(list(col1 = 1:5, col2 = c(1, 1, 1, 1, 1)), class = "data.frame", row.names = c("a", 
"b", "c", "d", "e"))