adding annotation_custom with rasterGrob after function call - r

Question

Apologies for the title, I know it sucks.
I am trying to create a waterfall chart function. So, I am trying to create a basic plot, which people can configure however they wish. I ran into a problem, though, adding a gradient to the plot. For example:
I have this df:
> wfDF
category value sign id end start labels
1 Basic Materials 0.0024 pos 1 0.0024 0.0000 0.0024
2 Communications 0.0492 pos 2 0.0516 0.0024 0.0516
3 Consumer, Cyclical 0.0268 pos 3 0.0784 0.0516 0.0784
4 Consumer, Non-cyclical 0.0245 pos 4 0.1029 0.0784 0.1029
5 Diversified -0.0037 neg 5 0.0992 0.1029 0.1029
6 Energy -0.0040 neg 6 0.0952 0.0992 0.0992
7 Financial 0.0445 pos 7 0.1397 0.0952 0.1397
8 Industrial 0.0006 pos 8 0.1403 0.1397 0.1403
9 Technology -0.0059 neg 9 0.1344 0.1403 0.1403
10 Total 0.1345 pos 10 0.0000 0.1344 0.1344
With this code:
ggplot(wfDF, aes(category, fill = sign, color = sign)) + guides(fill = FALSE, color=FALSE) +
ggtitle("Risk by Industry") +
annotation_custom(g, xmin=-Inf, xmax=Inf, ymin=-Inf, ymax=Inf) +
theme(plot.title = element_text(vjust=1.5, face="bold", size = 20),
axis.title.x = element_blank(), axis.title.y = element_blank()) +
geom_rect(aes(x = category, xmin = id - 0.475, xmax = id + 0.475, ymin = end, ymax = start)) +
scale_fill_manual(values=c("red", "forestgreen")) +
scale_color_manual(values=c("black", "black")) +
scale_y_continuous(labels = percent) +
scale_x_discrete("", breaks = levels(wfDF$category), labels = gsub(" ", "\n", levels(wfDF$category))) +
geom_text(data = wfDF, aes(id, labels, label = paste0(value*100, "%")), vjust = -.5, size = 5, fontface = 4)
Which produces this graph:
Which looks great. I am trying to write a function which will do all this with any set of categories and values, and allows for any colors or customization to be added or used. I have this function:
waterfall <- function(categories, values, has.total = FALSE, offset = .475, labelType = c("decimal", "percent")) {
library(scales)
library(grid)
library(ggplot2)
library(dplyr)
theData <- data.frame("category" = as.character(categories), "value" = as.numeric(values))
if (labelType == "percent") theData$value = theData$value/100
if (!has.total) theData <- theData %>% rbind(.,list("Total", sum(.$val)))
theData$sign <- ifelse(theData$val >= 0, "pos","neg")
theData <- data.frame(category = factor(theData$category, levels = unique(theData$category)),
value = round(theData$value,4),
sign = factor(theData$sign, levels = unique(theData$sign)))
theData$id <- seq_along(theData$value)
theData$end <- cumsum(theData$value)
theData$end <- c(head(theData$end, -1), 0)
theData$start <- c(0, head(theData$end, -1))
theData$labels <- paste0(theData$value*100, "%")
theData$labellocs <- pmax(theData$end,theData$start)
theGG <- ggplot(theData, aes(category, fill = sign, color = sign)) +
geom_rect(aes(x = category, xmin = id - offset, xmax = id + offset, ymin = end, ymax = start)) +
scale_x_discrete("", breaks = levels(theData$category), labels = gsub(" ", "\n", levels(theData$category))) +
geom_text(data = theData, aes(id, labellocs, label = labels), vjust = -.5, size = 5, fontface = 4)
return(theGG)
}
waterfall(categories = riskDecomp$ID, values = riskDecomp$val, labelType = "percent")
Which produces a pretty ugly basic thing:
However, if I try to run something like the following:
test <- waterfall(categories = riskDecomp$ID, values = riskDecomp$val, labelType = "percent")
g <- rasterGrob(blues9, width=unit(1,"npc"), height = unit(1,"npc"), interpolate = TRUE)
test + guides(fill = FALSE, color=FALSE) +
ggtitle("Risk Decomposition") +
annotation_custom(g, xmin=-Inf, xmax=Inf, ymin=-Inf, ymax=Inf) +
theme(plot.title = element_text(vjust=1.5, face="bold", size = 20),
axis.title.x = element_blank(), axis.title.y = element_blank()) +
scale_fill_manual(values=c("red", "forestgreen")) +
scale_color_manual(values=c("black", "black")) +
scale_y_continuous(labels = percent)
I get this nonsense:
The rasterGrob thing seems to overlay the entire rest of the plot. The only workaround I can find is to add the gradient to the inside of the function. Which kind of removes the... customization of the function. Is there a way to fix this? To fix the order of the grobs? If that makes sense?

Answer 1

you can change the order of the layers manually,
library(grid)
library(ggplot2)
g <- rasterGrob(matrix(blues9, ,1), interpolate=TRUE,
width=unit(1,"npc"), height=unit(1,"npc"))
p <- qplot(rnorm(10), rnorm(10)) +
annotation_custom(g)
nl <- length(p$layers)
p$layers <- c(p$layers[[nl]], p$layers[-nl])
p