R ggplot：按索引指定 aes

发布于 2024-09-17 10:58:51 字数 412 浏览 3 评论 0原文

ggplot() +
layer(
 data = diamonds, mapping = aes(x = carat, y = price),
 geom = "point", stat = "identity"
)

在上面的示例中，我想知道是否可以通过索引指定“aes”函数的参数。

我知道克拉和价格对应于钻石名称数组中的第 1 个和第 8 个元素。您能解释一下为什么以下不起作用吗？

ggplot() +
layer(
 data = diamonds, mapping = aes(x = names(diamonds)[1], y = names(diamonds)[8]),
 geom = "point", stat = "identity"
)

谢谢，德里克

原文

ggplot() +
layer(
 data = diamonds, mapping = aes(x = carat, y = price),
 geom = "point", stat = "identity"
)

In the above example, I am wondering if I can specify the parameters for the "aes" function by indexes.

I know that carat and price correspond to the 1st and 8th elements in the names array of diamond. Can you explain why the following does not work?

ggplot() +
layer(
 data = diamonds, mapping = aes(x = names(diamonds)[1], y = names(diamonds)[8]),
 geom = "point", stat = "identity"
)

Thanks, Derek

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余厌 2024-09-24 10:58:51

第二个版本不起作用，因为 names(diamonds)[1] 是 "carat" 而不是 carat。使用 aes_string 而不是 aes 来实现此目的。

ggplot( data = diamonds, mapping = aes_string(x = names(diamonds)[1], y = names(diamonds)[8]), stat = "identity")+ geom_point()

编辑：
要处理包含非法字符的名称，您必须将它们括在反引号中（任何时候您想使用它们时都是如此）：

dd <- data.frame(1:10, rnorm(1:10))
names(dd) <- c("(PDH-TSV 4.0)(ET)(240)", "Y")
nms <- paste("`", names(dd), "`", sep="")
ggplot(dd, mapping=aes_string(x=nms[1], y=nms[2])) + geom_point()

The second version does not work because names(diamonds)[1] is "carat" and not carat. Use aes_string instead of aes for this to work.

ggplot( data = diamonds, mapping = aes_string(x = names(diamonds)[1], y = names(diamonds)[8]), stat = "identity")+ geom_point()

EDIT:
To deal with names that have illegal characters, you have to do enclose them in backticks (that's the case any time you want to use them):

dd <- data.frame(1:10, rnorm(1:10))
names(dd) <- c("(PDH-TSV 4.0)(ET)(240)", "Y")
nms <- paste("`", names(dd), "`", sep="")
ggplot(dd, mapping=aes_string(x=nms[1], y=nms[2])) + geom_point()

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