r - R中带有gganimate的动画地理地图(Animated Geographical Maps in R with gganimate)

Question

I can generate some decent-looking choropleth maps in R, see for instance the following

(我可以在R中生成一些看起来不错的Choropleth贴图，例如，请参见以下内容)

library(tidyverse)
library(rnaturalearth) 
library(rnaturalearthdata)

set.seed(1234)

ww <- ne_countries(scale = "medium", returnclass = "sf")

ll <- ww$name %>% length

val <- sample(c("a","b","c","d"), ll, replace=T)
bb <- ne_download(type = "wgs84_bounding_box", category = "physical",
              returnclass = "sf")

ww <- ww %>% mutate(value=val)


gpl1 <- ggplot(data = ww) +
geom_sf(aes(fill=value),  col = "black", lwd = 0.3 )+
xlab(NULL) + ylab(NULL) +
ggtitle("World Export of Merchandise")+
geom_sf(data = bb, col = "grey", fill = "transparent") +
theme(plot.background = element_rect(fill = "white"),
      panel.background = element_rect(fill = 'white'),
      panel.grid.major = element_line(colour = "grey"),
      legend.position="top",
      plot.title = element_text(lineheight=.8, size=24, face="bold",
                                vjust=1),
      legend.text = element_text(vjust=.4,lineheight=1,size = 14),
      legend.title = element_text(vjust=1,lineheight=1, size=14,
                                  face="bold" ))+
coord_sf(crs = "+proj=eqearth +wktext") 

ggsave("test_world1.pdf", gpl1, width=6*1.618,height=5)

but then suppose that I have data for several years, for instance

(但是假设我有几年的数据，例如)

values_years <- tibble(value=sample(c("a","b","c","d"), 4*ll, replace=T),
            years=sample(seq(4), 4*ll, replace=T))

does anyone know how to use gganimate to generate a choropleth map where the country colors change automatically while showcasing different years?

(有谁知道如何使用gganimate生成一个Choropleth地图，在展示不同年份的同时，国家/地区的颜色会自动改变？)

I am not looking for an interactive viz, but something like this

(我不是在寻找交互式的视觉，而是类似这样的东西)

https://www.blog.cultureofinsight.com/2017/09/animated-choropleth-maps-in-r/

(https://www.blog.cultureofinsight.com/2017/09/animated-choropleth-maps-in-r/)

just I am having a hard time to simplify that example to my needs.

(只是我很难根据自己的需要简化该示例。)

Any help is appreciated!

(任何帮助表示赞赏！)

  ask by larry77 translate from so

Answer 1

I'm not an expert at either geospatial data or gganimate, but I managed to get something that resembles an answer to your question by doing the following.

(我既不是地理空间数据专家也不是地理专家，但我通过执行以下操作设法获得了类似于您问题的答案的东西。)

We'll start out in a similar fashion to how you started your example, but we also load the gganimate package.

(我们将以与您开始示例类似的方式开始，但是我们还将加载gganimate程序包。)

library(tidyverse)
library(rnaturalearth) 
library(rnaturalearthdata)
library(gganimate) # also needs transformr

## Do all previous stuff
set.seed(1234)

ww <- ne_countries(scale = "medium", returnclass = "sf")

ll <- ww$name %>% length

val <- sample(c("a","b","c","d"), ll, replace=T)
bb <- ne_download(type = "wgs84_bounding_box", category = "physical",
                  returnclass = "sf")
ww <- ww %>% mutate(value=val)

Then, for each of our timepoints, we copy the data and assign a group per shape, timepoint and new fill variable.

(然后，对于每个时间点，我们复制数据并为每个形状，时间点和新的填充变量分配一个组。)

The grouping is need because by default, the fill will determine the grouping and the animations will show countries all jumping across the map.

(需要分组是因为默认情况下，填充将确定分组，并且动画将显示在地图上跳跃的国家/地区。)

newdf <- lapply(seq_len(5), function(i) {
  new <- ww
  new$group <- seq_len(nrow(new))
  new$value <- sample(letters[1:4], nrow(new), replace = TRUE)
  new$time <- i
  new
})
newdf <- do.call(rbind, newdf)

Then we make a plot.

(然后我们作图。)

The main difference is that I assign a group in the geom_sf() and add transition_time(time) .

(主要区别在于我在geom_sf()分配了一个组，并添加了transition_time(time) 。)

Also, I add a subtitle to keep track of the animation state.

(另外，我添加了一个字幕来跟踪动画状态。)

gpl1 <- ggplot(data = newdf) +
  geom_sf(aes(fill=value, group = group),  col = "black", lwd = 0.3 )+
  xlab(NULL) + ylab(NULL) +
  ggtitle("World Export of Merchandise", subtitle = "{frame_time}")+
  geom_sf(data = bb, col = "grey", fill = "transparent") +
  theme(plot.background = element_rect(fill = "white"),
        panel.background = element_rect(fill = 'white'),
        panel.grid.major = element_line(colour = "grey"),
        legend.position="top",
        plot.title = element_text(lineheight=.8, size=24, face="bold",
                                  vjust=1),
        legend.text = element_text(vjust=.4,lineheight=1,size = 14),
        legend.title = element_text(vjust=1,lineheight=1, size=14,
                                    face="bold" )) +
  transition_time(time)
  # coord_sf(crs = "+proj=eqearth +wktext") # couldn't get this coord to work

And then we animate:

(然后我们制作动画：)

ani <- animate(gpl1)