有时使用CasperJS表单填写和捕获失败(Form fill and capture fail sometimes using CasperJS)

 以下是此帖后的解决方案。 它使用edit_colors()包中的edit_colors()函数。 （免责声明：我是该套餐的作者。） 
 
p <- ggplot(economics) +
  aes(unemploy, psavert) +
  geom_point() +
  geom_smooth(se = F) +
  ggtitle('Unemploy vs Personal Savings Rate')

library(colorblindr) # devtools::install_github("clauswilke/colorblindr")
library(colorspace) # install.packages("colorspace", repos = "http://R-Forge.R-project.org") --- colorblindr requires the development version
# need also install cowplot; current version on CRAN is fine.

# modify alpha values using the alpha function from the scales package
p_alpha <- edit_colors(p, scales::alpha, alpha = .5)

# print
grid::grid.newpage()
grid::grid.draw(p_alpha)
 
  
 
 缩放的alpha()函数的一个缺点是它替换了alpha值，它没有组合alpha值。 所以这里有一个简单的例子，说明如何使用自己的alpha组合函数组合alpha值： 
 
mult_alpha <- function(color, alpha = .5) 
{
  col <- grDevices::col2rgb(color, TRUE)/255
  new_col <- grDevices::rgb(col[1, ], col[2, ], col[3, ], alpha*col[4, ])
  new_col[is.na(color)] <- NA
  new_col
}

p2 <- ggplot(iris, aes(Sepal.Length, fill = Species)) +
  geom_density(alpha = .3) + theme_bw()

p2_mult_alpha <- edit_colors(p2, mult_alpha, alpha = .7)
 
 两种方法之间的比较表明，它们对已经具有一定透明度的图形给出了截然不同的结果： 
 
p2_alpha <- edit_colors(p2, scales::alpha, alpha = .7)

cowplot::plot_grid(p2_alpha, p2_mult_alpha)
 
  
 
 （左图：使用尺度的alpha ;右图：使用mult_alpha定义的mult_alpha 。） 

Here is a solution following this post. It uses the edit_colors() function from the colorblindr package. (Disclaimer: I'm an author of that package.)
 
p <- ggplot(economics) +
  aes(unemploy, psavert) +
  geom_point() +
  geom_smooth(se = F) +
  ggtitle('Unemploy vs Personal Savings Rate')

library(colorblindr) # devtools::install_github("clauswilke/colorblindr")
library(colorspace) # install.packages("colorspace", repos = "http://R-Forge.R-project.org") --- colorblindr requires the development version
# need also install cowplot; current version on CRAN is fine.

# modify alpha values using the alpha function from the scales package
p_alpha <- edit_colors(p, scales::alpha, alpha = .5)

# print
grid::grid.newpage()
grid::grid.draw(p_alpha)
 
 
One downside of the alpha() function from scales is that it replaces the alpha value, it doesn't combine alpha values. So here is a simple example of how you can combine alpha values, using your own alpha combination function:
 
mult_alpha <- function(color, alpha = .5) 
{
  col <- grDevices::col2rgb(color, TRUE)/255
  new_col <- grDevices::rgb(col[1, ], col[2, ], col[3, ], alpha*col[4, ])
  new_col[is.na(color)] <- NA
  new_col
}

p2 <- ggplot(iris, aes(Sepal.Length, fill = Species)) +
  geom_density(alpha = .3) + theme_bw()

p2_mult_alpha <- edit_colors(p2, mult_alpha, alpha = .7)
 
Comparison between the two approaches shows that they give very different results for plots that already have some transparency:
 
p2_alpha <- edit_colors(p2, scales::alpha, alpha = .7)

cowplot::plot_grid(p2_alpha, p2_mult_alpha)
 
 
(left image: using alpha from scales; right image: using mult_alpha as defined above.)