在ggplot2中添加手册图例？

Question

我正在做一个对同一时间序列数据的两个不同估计的比较图表。如果原始估计值大于最新估计值，我将填入两个绿色系列之间的区域，否则将填入红色区域。

我已经有了这部分工作，但我想添加一个填充颜色的图例。我试着朝着代码底部尝试scale_fill_manual，但它似乎没有做任何事情？

下面的代码：

library(ggplot2) 
library(scales) 
library(colorspace) 

# Return a polygon that only plots between yLower and yUpper when yLower is 
# less than yUpper. 
getLowerPolygon = function(x, yLower, yUpper) { 
    # Create the table of coordinates 
    poly = data.frame(
     x = numeric(), 
     y = numeric()) 

    lastReversed = (yUpper[1] < yLower[1]) 
    for (r in 1:length(x)) { 
     reversed = (yUpper[r] < yLower[r]) 
     if (reversed != lastReversed) { 
      # Between points r-1 and r, the series intersected, so we need to 
      # change the polygon from visible to invisible or v.v. In either 
      # case, just add the intersection between those two segments to the 
      # polygon. Algorithm from: 
      # https://en.wikipedia.org/wiki/Line-line_intersection 
      # First line: x1,y1 - x2,y2 
      x1 = x[r-1] 
      y1 = yLower[r-1] 
      x2 = x[r] 
      y2 = yLower[r] 
      # Second line: x3,y3 - x4,y4 
      x3 = x[r-1] 
      y3 = yUpper[r-1] 
      x4 = x[r] 
      y4 = yUpper[r] 
      # Calculate determinants 
      xy12 = det(matrix(c(x1, y1, x2, y2), ncol = 2)) 
      xy34 = det(matrix(c(x3, y3, x4, y4), ncol = 2)) 
      x12 = det(matrix(c(x1, 1, x2, 1), ncol = 2)) 
      x34 = det(matrix(c(x3, 1, x4, 1), ncol = 2)) 
      y12 = det(matrix(c(y1, 1, y2, 1), ncol = 2)) 
      y34 = det(matrix(c(y3, 1, y4, 1), ncol = 2)) 
      # Calculate fraction pieces 
      xn = det(matrix(c(xy12, x12, xy34, x34), ncol = 2)) 
      yn = det(matrix(c(xy12, y12, xy34, y34), ncol = 2)) 
      d = det(matrix(c(x12 , y12, x34, y34), ncol = 2)) 
      # Calculate intersection 
      xi = xn/d 
      yi = yn/d 
      # Add the point 
      poly[nrow(poly)+1,] = c(xi, yi) 
     } 
     lastReversed = reversed 
     # http://stackoverflow.com/questions/2563824 
     poly[nrow(poly)+1,] = c(x[r], min(yLower[r], yUpper[r])) 
    } 

    poly = rbind(poly, data.frame(
     x = rev(x), 
     y = rev(yUpper))) 

    return(poly) 
} 

getComparisonPlot = function(data, title, lower_name, upper_name, 
         x_label, y_label, legend_title = '') { 

    lightGreen = '#b0dd8d' 
    lightRed = '#fdba9a' 

    darkGray = RGB(.8, .8, .8) 
    midGray = RGB(.5, .5, .5) 

    plot = ggplot(data, aes(x = x)) 

    plot = plot + geom_polygon(
     aes(x = x, y = y), 
     data = data.frame(
      x = c(data$x, rev(data$x)), 
      y = c(data$yLower, rev(data$yUpper)) 
     ), 
     fill = lightRed) 

    coords = getLowerPolygon(data$x, data$yLower, data$yUpper) 

    plot = plot + geom_polygon(
     aes(x = x, y = y), 
     data = coords, 
     fill = lightGreen) 

    plot = plot + geom_line(
     aes(y = yUpper, color = 'upper'), 
     size = 0.5) 

    plot = plot + geom_line(
     aes(y = yLower, color = 'lower'), 
     size = 0.5) 

    plot = plot + 
     ggtitle(paste(title, '\n', sep='')) + 
     xlab(x_label) + 
     ylab(y_label) + 
     scale_y_continuous(labels = comma) 

    # http://stackoverflow.com/a/10355844/106302 
    plot = plot + scale_color_manual(
     name = legend_title, 
     breaks = c('upper' , 'lower'), 
     values = c('gray20', 'gray50'), 
     labels = c(upper_name, lower_name)) 

    plot = plot + scale_fill_manual(
     name = 'Margin', 
     breaks = c('upper', 'lower'), 
     values = c(lightGreen, lightRed), 
     labels = c('Over', 'Under')) 

    return(plot) 
} 

print(getComparisonPlot(
    data = data.frame(
     x = 1:20, 
     yLower = 1:20 %% 5 + 2, 
     yUpper = 1:20 %% 7 
    ), 
    title = 'Comparison Chart', 
    lower_name = 'Latest', 
    upper_name = 'Original', 
    x_label = 'X axis', 
    y_label = 'Y axis', 
    legend_title = 'Thing' 
)) 

以下是图表的形象，我觉得这是一个很酷的技术：

我也开到了改善任何其他建议我的ggplot代码。

Answer 1

GGplot需要您将多边形fill唯美图映射到某个变量。或者，在这种情况下，它只需要你“标记”多边形的类型（即“上”和“下”）。您可以通过传递一个带有相应标签的字符串来填充geom_polygon（）的美感。你正在做的是为每个多边形传递给定的颜色，而不是映射到ggplot将理解的任何东西。这是一种“硬编码颜色”= P。

嗯，这里是内部getComparisonPlot的变化：

plot = plot + geom_polygon(
    aes(x = x, y = y, fill = "upper"), 
    data = coords) 

plot = plot + geom_polygon(
    aes(x = x, y = y, fill = "lower"), 
    data = data.frame(
     x = c(data$x, rev(data$x)), 
     y = c(data$yLower, rev(data$yUpper)) 
    )) 

一两件事。请注意，通过填充审美的字符串与传递给scale_fill_manual的中断相符。有必要让传奇地图的事情正确。

plot = plot + scale_fill_manual(
    name = 'Margin', 
    breaks = c('upper', 'lower'), # <<< corresponds to fill aesthetic labels 
    values = c(lightGreen, lightRed), 
    labels = c('Over', 'Under')) 

结果：

希望它帮助。