ggplot2和gganimate：如何使动画线根据Y轴值改变颜色

Question

我想让我的情节中的动画线在颜色高于50％时改变颜色，以显示结果的差异。

我 “data.thesis” 框架是这样的：

我假设的结局情节是在这里。从而使黑线移动到可能的结果的代码将动画的情节：

library(ggplot2) 
library(gganimate) 

z <- qnorm(0.33) 
sd <- (50 - 55)/z 
moe <- 1.96*sd 

data.thesis <- data.frame(name = "Candidate", percent.vote = 55) 
data.thesis <- data.thesis %>% 
    mutate(sd = sd, 
     ymin = percent.vote - 1.96*sd, 
     ymax = percent.vote + 1.96*sd) 


set.seed(2016) 
n.outcomes <- 50 

df <- data.frame(simulation = 1:n.outcomes, 
       team = "Yes", 
       vote.share = round(rnorm(50, mean = 55, sd = sd), 3)) 

p <- df %>% 
    ggplot(aes(x = team, y = vote.share)) + 
    geom_errorbar(aes(
    ymin = vote.share, ymax = vote.share, 
    frame = simulation, cumulative = TRUE), 
    color = "grey80", alpha = 1/8) + 
    geom_errorbar(aes(
    ymin = vote.share, ymax = vote.share, frame = simulation), 
    color = "black") + 
    theme(panel.background = element_rect(fill = "#FFFFFF"), 
     text=element_text(size=15, vjust=1, family="Verdana"), 
     axis.title.x=element_blank(), 
     axis.text.x=element_blank(), 
     axis.ticks.x=element_blank()) + 
    labs(title = "", y = "Vote share", x = "") + 
    scale_y_continuous(limits=c(0, 100), 
        breaks=c(0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100)) + 
    xlab("") + 
    ylab("Percent") + 
    ggtitle("Treatment 2: Hypothetical Outcome Plot") + 
    annotate("segment", x=1.6, xend=1.6, y=51, yend=70, colour="black", size=1, arrow=arrow()) + 
    annotate(geom="text", x=1.6, y=74, label="A Wins", color="black", size=5) + 
    annotate("segment", x=1.6, xend=1.6, y=49, yend=30, colour="black", size=1, arrow=arrow()) + 
    annotate(geom="text", x=1.6, y=26, label="A Loses", color="black", size=5) + 
    annotate("text", x = 1.8, y = 75, label = "") + 
    annotate("segment", x=.55, xend=1.45, y=55, yend=55, colour="red") 

gganimate(p, title_frame = FALSE) 

Answer 1

而不是硬编码的线条颜色，用色彩美学在第二次调用geom_errorbar。具体来说，改变从这个第二geom_errorbar声明：

geom_errorbar(aes(ymin = vote.share, ymax = vote.share, frame = simulation), 
    color = "black") + 

这样：

geom_errorbar(aes(ymin = vote.share, ymax = vote.share, frame = simulation, 
    colour=ifelse(vote.share > 50, "Win","Lose")), show.legend=FALSE) + 

这是不特定于gganimate，因为这是你会怎么做任何ggplot使线颜色取决于超过某个y轴切割点。

在下面的图中，我添加了+ scale_colour_manual(values=c(Win="blue", Lose="red"))，但您可以将颜色设置为您希望的任何值。另外，我在y = 55处留下了红线标注。我不确定你是否想在最后的情节中，但它当然可以很容易地被删除。