r - 如何使用 gganimate 包在 R 中绘制动态地图？

Question

据我所知 gganimate 已经在 1.0.3 版本中，我们可以使用transition_*函数来绘制动态图。但是当我运行以下代码时，出现错误：

Error in `$<-.data.frame`(`*tmp*`, "group", value = "") : 
  replacement has 1 row, data has 0

代码：

library(ggmap)
library(gganimate)
world <- map_data("world")
world <- world[world$region!="Antarctica",]
data <- data.frame(state = c("Alabama","Alaska","Alberta","Alberta","Arizona"),
                   lon = c(-86.55,-149.52,-114.05,-113.25,-112.05),
                   lat = c(33.30,61.13,51.05,53.34,33.30)
                   )
ggplot()+
  geom_map(data = world,
           map = world,
           aes(long,lat,map_id = region),
           color = '#333300',
           fill = '#663300') +
  geom_point(data = data,
             aes(x = lon, y = lat),
             size = 2.5) +
  geom_jitter(width = 0.1) +
  transition_states(states = state)

标签： rggplot2gganimate

Answer 1

您没有在顶层ggplot()行中定义数据，因此stateintransition_*无处不在。

我也不清楚为什么你geom_jitter的代码中有一个级别。就像transition_*，它没有要继承的顶级数据/美学映射，所以它也会抛出错误，transition_*没有首先触发错误。此外，即使我们添加映射，考虑到数据中的纬度/经度坐标范围，0.1 的抖动在视觉上也几乎没有影响。

您可以尝试以下方法：

# put data in top level ggplot()
ggplot(data,
       aes(x = lon, y = lat))+
  geom_map(data = world,
           map = world,
           aes(long,lat,map_id = region),
           color = '#333300', fill = '#663300',
           # lighter background for better visibility
           alpha = 0.5) + 
  geom_point(size = 2.5) +
  # limit coordinates to relevant range
  coord_quickmap(x = c(-180, -50), y = c(25, 85)) +
  transition_states(states = state)