ggplot点中的轻微点笔触 [英] Slight point strokes in ggplot points

问题描述

请考虑以下内容:

库(ggplot2)

df = data.frame(x = rep(0,9), y = rep(0,9), alp = c(1:8/20,1))
ggplot(df) + 
  geom_point(aes(x, y, alpha=alp), size = 20, col = 'red') + 
  theme_minimal() + facet_wrap(~ alp) + guides(alpha = F)

如您所见，有一些模糊的轮廓.它使覆盖许多低透明度的点看起来有点像frogspawn.这只是Mac的东西吗?知道如何删除它吗?

As you can see there are feint outlines. It makes overlaying many low-transparency points look a bit like frogspawn. Is this just a Mac thing? Any idea how to remove it?

推荐答案

ggplot2的默认点形状为 pch = 19 .这不是可以单独控制其边框颜色和内部颜色的要点之一；例如，在下文中， fill ='black'无效.

The default point shape for ggplot2 is pch = 19. It's not one of those points where the colour of its border and its inside can be controlled separately; for instance, in the following, fill = 'black' has no effect.

library(ggplot2)

df = data.frame(x =runif(1000), y = runif(1000))

p = ggplot(df) + 
geom_point(aes(x, y), alpha = .1, size = 5, fill = 'black', colour = 'red') +                                        
  theme_bw() 
p

但是该点确实具有边界线.线的宽度可以用 stroke 更改；如下:

Yet the point does have a boundary line. The line's width can be changed with stroke; as follows:

p = ggplot(df) + 
geom_point(aes(x, y), stroke = 2, alpha = .1, size = 5, fill = 'black', colour = 'red') +                                        
  theme_bw() 
p

不幸的是，将笔划设置为零不会删除边界线.似乎有一个下限.

Unfortunately, setting stroke to zero will not remove the boundary line; it seems there is a lower limit.

要删除边界线，请使用具有可操纵边界的形状之一；例如， shape = 21 .将其填充"设置为红色，将其颜色"设置为透明.

To remove the boundary line, use one of the shapes that has a border that can be manipulated; for instance, shape = 21. Set its "fill" to red and its "colour" to transparent.

p = ggplot(df) + 
geom_point(aes(x, y), shape = 21, alpha = .1, size = 5, fill = 'red', colour = 'transparent') +                                      
  theme_bw() 
p

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