ggplot 图例问题与 geom_point 和 geom_text
我试图使用geom_point来说明我的数据计数。我还想用 geom_text 注释图表中的一些点。当我添加对 geom_text 的调用时，它似乎正在图例中的点下方绘制一些内容。我尝试颠倒图层的顺序，但无济于事。我无法理解为什么要这样做。有人见过这个吗？
set.seed(42)
df <- data.frame(x = 1:10
, y = 1:10
, label = sample(LETTERS,10, replace = TRUE)
, count = sample(1:300, 10, replace = FALSE)
)
p <- ggplot(data = df, aes(x = x, y = y, size = count)) + geom_point()
p + geom_text(aes(label = label, size = 150, vjust = 2))
I am trying to use geom_point to illustrate the count of my data. I would also like to annotate a few of the points in my graph with geom_text. When I add the call to geom_text, it appears that it is plotting something underneath the points in the legend. I've tried reversing the order of the layers to no avail. I can't wrap my head around why it is doing this. Has anyone seen this before?
set.seed(42)
df <- data.frame(x = 1:10
, y = 1:10
, label = sample(LETTERS,10, replace = TRUE)
, count = sample(1:300, 10, replace = FALSE)
)
p <- ggplot(data = df, aes(x = x, y = y, size = count)) + geom_point()
p + geom_text(aes(label = label, size = 150, vjust = 2))
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这种事一直发生在我身上。诀窍在于了解
aes()将数据映射到美学。如果没有要映射的数据（例如，如果您确定了单个值），则没有理由使用aes()。我相信只有aes()内部的内容才会出现在您的图例中。此外，当您在 ggplot(aes()) 内部指定映射时，这些映射将应用于每个后续层。这对您的 x 和 y 有好处，因为
geom_point和geom_text都使用它们。这对size = count不利，因为它仅适用于点。因此，这是我防止此类事情发生的两条规则：
aes()内部。如果参数采用单个预先确定的值，请将其传递到aes()的外部层。所以我会这样绘制：
This happened to me all the time. The trick is knowing that
aes()maps data to aesthetics. If there's no data to map (e.g., if you have a single value that you determine), there's no reason to useaes(). I believe that only things inside of anaes()will show up in your legend.Furthermore, when you specify mappings inside of
ggplot(aes()), those mappings apply to every subsequent layer. That's good for your x and y, since bothgeom_pointandgeom_textuse them. That's bad forsize = count, as that only applies to the points.So these are my two rules to prevent this kind of thing:
aes(). If the argument is taking a single pre-determined value, pass it to the layer outside ofaes().ggplot(aes())if you're confident that every subsequent layer will use it. Otherwise, map it at the layer level.So I would plot this thusly:
或者，如果您需要指定 aes 内文本的大小，则 legend = FALSE 禁止绘制几何图例：
or, if you need to specify the size of text inside the aes, then legend = FALSE suppress drawing the legends of the geom: