R:如何在ggplot2线图中重新排序图例键以匹配每个系列中的最终值？

Question

我正在使用ggplot2绘制线图,显示多个仪器的价格随时间的变化.我成功地在图上获得了多行,并添加了显示最近价格变化的值.我想要做的(并且还没有实现)是重新排序图例键,以便最高涨的价格系列位于图例的顶部,然后是价格系列的关键,该价格序列的价格上涨第二,等等.

在下图中,图例按字母顺序显示键.我想要做的是以DDD,AAA,CCC然后BBB的顺序显示图例关键条目,这是最近日期的性能顺序.我怎样才能做到这一点？

最小代码如下.

require(ggplot2)
require(scales)
require(gridExtra)
require(lubridate)
require(reshape)

# create fake price data
set.seed(123)
monthsback <- 15
date <- as.Date(paste(year(now()), month(now()),"1", sep="-")) - months(monthsback)
mydf <- data.frame(mydate = seq(as.Date(date), by = "month", length.out = monthsback),
                      aaa = runif(monthsback, min = 600, max = 800),
                      bbb = runif(monthsback, min = 100, max = 200),
                      ccc = runif(monthsback, min = 1400, max = 2000),
                      ddd = runif(monthsback, min = 50, max = 120))

# function to calculate change
change_from_start <- function(x) {
   (x - x[1]) / x[1]
}

# for appropriate columns (i.e. not date), replace fake price data with change in price
mydf[, 2:5] <- lapply(mydf[, 2:5], function(myparam){change_from_start(myparam)})

# get most recent values and reshape
myvals <- mydf[mydf$mydate == mydf$mydate[nrow(mydf)],]
myvals <- melt(myvals, id = c('mydate'))

# plot multiple lines
p <- ggplot(data = mydf) +
    geom_line( aes(x = mydate, y = aaa, colour = "AAA"), size = 1) +
    geom_line( aes(x = mydate, y = bbb, colour = "BBB"), size = 1) +
    geom_line( aes(x = mydate, y = ccc, colour = "CCC"), size = 1) +
    geom_line( aes(x = mydate, y = ddd, colour = "DDD"), size = 1) +
    scale_colour_manual("", values = c("AAA" = "red", "BBB" = "black", "CCC" = "blue", "DDD" = "green")) +
    scale_y_continuous(label = percent_format()) +
    geom_text(data = myvals, aes(x = mydate + 30, y = value, label = sprintf("%+1.1f%%", myvals$value * 100)), size = 4, colour = "grey50") +
    opts(axis.title.y = theme_blank()) +
    opts()

# and output
print(p)

Answer 1

试试这个:

mydf <- melt(mydf,id.var = 1)
mydf$variable <- factor(mydf$variable,levels = rev(myvals$variable[order(myvals$value)]),ordered = TRUE)

# plot multiple lines
p <- ggplot(data = mydf) +
    geom_line(aes(x = mydate,y = value,colour = variable,group = variable),size = 1) +
    scale_colour_manual("", values = c("aaa" = "red", "bbb" = "black", "ccc" = "blue", "ddd" = "green")) +
    scale_y_continuous(label = percent_format()) +
    geom_text(data = myvals, aes(x = mydate + 30, y = value, label = sprintf("%+1.1f%%", myvals$value * 100)), 
                size = 4, colour = "grey50") +
    opts(axis.title.y = theme_blank()) +
    opts()

# and output
print(p)

我融化了您的完整数据集,为您节省了几行用于绘制代码.像往常一样,关键是要确保变量是有序因子.

为了解决在评论中出现的问题,你可以通过你喜欢出现在传说本身,只要你得到正确的顺序任何标签:

ggplot(data = mydf) +
    geom_line(aes(x = mydate,y = value,colour = variable,group = variable),size = 1) +
    scale_colour_manual("", values = c("aaa" = "red", "bbb" = "black", "ccc" = "blue", "ddd" = "green"),labels = c('Company D','Company A','Company C','Company B')) +
    scale_y_continuous(label = percent_format()) +
    geom_text(data = myvals, aes(x = mydate + 30, y = value, label = sprintf("%+1.1f%%", myvals$value * 100)), 
                size = 4, colour = "grey50") +
    opts(axis.title.y = theme_blank()) +
    opts()

注:自版本0.9.2 opts已经被替代的theme,如:

+ theme(axis.title.y = element_blank())