[英]How can I apply a gradient fill to a geom_rect object in ggplot2?
I'm in the midst of building a time series line chart using ggplot2 that utilises geom_rect objects to highlight a particular time series event. 我正在使用ggplot2构建时间序列折线图,该图使用geom_rect对象来突出显示特定的时间序列事件。
For purely aesthetic reasons I'm interested in applying a gradient to the geom_rect object so that it fades to white/transparent as y increases. 出于纯粹的美学原因,我有兴趣将渐变应用于geom_rect对象,以便在y增加时渐变为白色/透明。
I have read other answers where it has been suggested that geom_tile or geom_raster may offer a solution. 我已经阅读了其他答案,其中有人建议geom_tile或geom_raster可以提供解决方案。 I've had no luck with this... to me geom_rect seems to be the obvious choice since I can specify the beginning and end of the time series as boundaries. 我对此没有运气......对我来说geom_rect似乎是明显的选择,因为我可以将时间序列的开头和结尾指定为边界。 However, I'm hoping that I can be proven wrong! 但是,我希望我被证明是错的! If anyone has any guidance, it would be very much appreciated. 如果有人有任何指导,将非常感谢。 My attempt thus far is: 我到目前为止的尝试是:
## READ DATA
file = "Data.csv"
timeSeries <- read.csv(file, header=TRUE)
## CONVERT DATA TO DATE CLASS
timeSeries$Date <- as.Date(timeSeries$Date, "%d/%m/%y")
timeSeries$Date <- as.Date(format(timeSeries$Date, "19%y-%m-%d"))
## SET GEOM_RECT DATA FRAME
event <- c("Event1", "Event2", "Event3")
startDate <- c("15/06/15", "12/07/17", "6/09/18")
finishDate <- c("9/01/16", "18/11/17", "5/11/18")
dates <- cbind(event, startDate, finishDate)
dates <- as.data.frame(dates, rownames=NULL, stringsAsFactors=FALSE)
dates$startDate <- as.Date(dates$startDate, "%d/%m/%y")
dates$startDate <- as.Date(format(dates$startDate, "19%y-%m-%d"))
dates$finishDate <- as.Date(dates$finishDate, "%d/%m/%y")
dates$finishDate <- as.Date(format(dates$finishDate, "19%y-%m-%d"))
## PLOT USING GGPLOT
plot <- ggplot(timeSeries) +
geom_rect(data=dates, aes(xmin=startDate, xmax=finishDate, ymin=0, ymax=25), fill="blue", alpha=0.4) +
geom_line(aes(x=Date, y=Event)) +
scale_x_date(labels=date_format("19%y")) +
ggtitle("") +
xlab("Time Series") +
ylab("Number") +
theme_minimal()
plot
The code above should produce this plot. 上面的代码应该产生这个图。 Data can be downloaded from here . 数据可以从这里下载。
Here's my implementation of @baptiste's idea. 这是我对@ baptiste的想法的实现。 Looks fancy! 看起来很花哨!
ggplot_grad_rects <- function(n, ymin, ymax) {
y_steps <- seq(from = ymin, to = ymax, length.out = n + 1)
alpha_steps <- seq(from = 0.5, to = 0, length.out = n)
rect_grad <- data.frame(ymin = y_steps[-(n + 1)],
ymax = y_steps[-1],
alpha = alpha_steps)
rect_total <- merge(dates, rect_grad)
ggplot(timeSeries) +
geom_rect(data=rect_total,
aes(xmin=startDate, xmax=finishDate,
ymin=ymin, ymax=ymax,
alpha=alpha), fill="blue") +
guides(alpha = FALSE)
}
ggplot_grad_rects(100, 0, 25) +
geom_line(aes(x=Date, y=Event)) +
scale_x_date(labels=date_format("19%y")) +
ggtitle("") +
xlab("Time Series") +
ylab("Number") +
theme_minimal()
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