Question

我使用image命令绘制矩阵，矩阵包含一些NA值。我正在使用image喜欢

image(figData, zlim = zRange, col = colors, useRaster=TRUE)

zRange小于figData的实际范围。我正在使用以下组中的顶部色彩图，这与红绿色感知缺陷兼容：

http://www.mathworks.com/matlabcentral/fx_files/31761/6/thumbnail_184481.jpg

我想为NA中figData以外的colors中的gray值选择特定颜色（例如，NA）。 colors值现在已映射到white（na.color）的最后一个元素，因此我无法将它们与超出范围的值区分开来。

理想情况下，无论我使用哪种调色板，我都希望有一种解决方案。

我想要heatmap.2中与image选项类似的内容，我该怎么做？我愿意修改image源代码来完成此操作，但是rasterImage似乎调用了image.nan <- function(z, zlim, col, na.color='gray', outside.below.color='black', outside.above.color='white',...) { zstep <- (zlim[2] - zlim[1]) / length(col); # step in the color palette newz.below.outside <- zlim[1] - zstep # new z for values below zlim newz.above.outside <- zlim[2] + zstep # new z for values above zlim newz.na <- zlim[2] + 2 * zstep # new z for NA z[which(z<zlim[1])] <- newz.below.outside # we affect newz.below.outside z[which(z>zlim[2])] <- newz.above.outside # we affect newz.above.outside z[which(is.na(z>zlim[2]))] <- newz.na # same for newz.na zlim[1] <- zlim[1] - zstep # extend lower limit to include below value zlim[2] <- zlim[2] + 2 * zstep # extend top limit to include the two new values above and na col <- c(outside.below.color, col, outside.above.color, na.color) # we construct the new color range by including: na.color and na.outside image(z=z, zlim=zlim, col=col, ...) # we finally call image(...) }函数，其源代码我找不到。

在接受了Jealie的回答之后，我在这里包含了代码，以便对低于和高于该范围的值进行不同的考虑：

{{1}}

Answer 1

小校正：外部的值未映射到col的最后一个元素，但它们根本没有被绘制（并且没有颜色看起来是白色的。）。

否则，要回答您的问题，最简单的方法是在image周围编写一个包装器，其中包含两个新参数：na.color和outside.color。以下是我的建议，对于NA值，默认为gray;对于white以外的值，默认为zlim：

my.image <- function(figData,  zlim, col, na.color='gray', outside.color='white', ...)
{
  newz.na <- zlim[2]+(zlim[2]-zlim[1])/length(col) # new z for NA
  newz.outside <- zlim[2]+2*(zlim[2]-zlim[1])/length(col) # new z for values outside zlim

  figData$z[which(is.na(figData$z>zlim[2]))] <- newz.na # we affect newz.outside
  figData$z[which(figData$z<zlim[1] | figData$z>zlim[2])] <- newz.outside # same for newz.na


  zlim[2] <- zlim[2]+2*(zlim[2]-zlim[1])/length(col) # we finally extend the z limits to include the two new values 

  col <- c(col, na.color, outside.color) # we construct the new color range by including: na.color and outside.color

  image(figData,  zlim=zlim, col=col, ...) # we finally call image(...)
}

Answer 2

因为颜色间隔定义为(*bottom*, *top*]，所以z中等于zlim [1]的值将使用outside.below.color着色（因为outside.below.color的范围是{{1 }}）。

以下版本修复了此错误：

( *zlim[1] - zstep* , *zlim[1]* ]

比较

image.nan.better <- function(z,  zlim, col, na.color='gray', outside.below.color='black', outside.above.color='white',...)
{
      zstep <- (zlim[2] - zlim[1]) / length(col); # step in the color palette
      newz.below.outside <- zlim[1] - 2 * zstep # new z for values below zlim
      newz.above.outside <- zlim[2] + zstep # new z for values above zlim
      newz.na <- zlim[2] + 2 * zstep # new z for NA

      z[which(z<zlim[1])] <- newz.below.outside # we affect newz.below.outside
      z[which(z>zlim[2])] <- newz.above.outside # we affect newz.above.outside
      z[which(is.na(z>zlim[2]))] <- newz.na # same for newz.na

      zlim[1] <- zlim[1] - 2 * zstep # extend lower limit to include below value
      zlim[2] <- zlim[2] + 2 * zstep # extend top limit to include the two new values above and na

      col <- c(outside.below.color, col[1], col, outside.above.color, na.color) #correct by including col[1] at bottom of range

      image(z=z,  zlim=zlim, col=col, ...) # we finally call image(...)
}

如何在图像绘图中为NA指定特定颜色

2 个答案: