在 R 中按类别着色点 [英] Coloring the points by category in R

问题描述

我正在使用以下代码在 R 中创建散点图:

I am creating a scatter plot in R using the following code:

plot(df_prob1$x1, df_prob1$x2, pch = df_prob1$y)

我得到以下情节:

如上图所示，有两类，一类用正方形表示，另一类用圆形表示.我希望这两个类别也有不同的颜色.

As seen in the above plot there are two categories, one represented by a square and the other by circle. I want these two categories to have different colors as well.

我确实尝试使用以下代码:

I did try using the following code:

plot(df_prob1$x1, df_prob1$x2, pch = df_prob1$y, col = c("red", "blue"))

我得到以下情节:

然而，它是随机着色点，没有考虑类别.

However, it is randomly coloring points and not taking the categories into consideration.

我也尝试将变量作为 col 的值传递:

I also did trying passing the variable as value for col as such:

plot(df_prob1$x1, df_prob1$x2, pch = df_prob1$y, col = df_prob1$y)

但这并没有给出正确的情节.

But this didn't give a proper plot.

推荐答案

诀窍是使用 df_prob1$y 作为颜色向量的索引，c("red", "蓝色").如果将列 y 强制转换为因子，则可以轻松完成此操作，因为因子在内部编码为从 1 开始的连续整数.以下代码使用内置数据集 iris，在此答案的末尾处理.

The trick is to use df_prob1$y as an index to the colors vector, c("red", "blue"). This can easily be done if the column y is coerced to a factor, since factors are coded internally as consecutive integers starting at 1. The following code uses the built-in data set iris, processed at the end of this answer.

clrs <- c("red", "blue")[factor(df_prob1$y)]
plot(df_prob1$x1, df_prob1$x2, pch = df_prob1$y, col = clrs)

测试数据.

set.seed(1234)
df_prob1 <- subset(iris[c(1, 2, 5)], Species != "virginica")
df_prob1 <- df_prob1[sample(nrow(df_prob1), 50), ]
df_prob1[[3]] <- as.numeric(df_prob1[[3]] == "setosa")
names(df_prob1) <- c("x1", "x2", "y")

这篇关于在 R 中按类别着色点的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！