gganimate showing transition along some objects

问题

I m trying to create animation to show transition along some nodes. I want to show point moving from SRC to TGT with transition change in intensity my df is like this below.

> df
  node intensity Lon Lat
1  SRC      0.90  40  60
2  TGT      0.89  80  40
3  TGT      0.80  40  30
4  TGT      0.99  30  20

library(ggplot2)
 library(gganimate)
 df <- read.table(text = "node intensity Lon Lat
                          SRC .9  40  60 
                            TGT .89 80   40
                            TGT  .8 40 30
                            TGT .99 30     20", header = TRUE)
 ggm <- ggplot(data = df, aes(x = Lon, y = Lat, size= intensity, colour=node)) +
      geom_point(alpha=.5)+
      transition_states(node)+
      labs(title = "test")+ 
      shadow_wake(wake_length = 0.5)

my desired output is to show moving animation something like this

I am getting point stationary SRC and TGT along frames

回答1:

You can get the desired effect by making three copies of the source and assigning a group to each point that should go from its source to target location.

https://cran.r-project.org/web/packages/gganimate/vignettes/gganimate.html

The key is the group aesthetic. You may be familiar with this aesthetic from plotting lines and polygons, but in gganimate it takes a more central place. Data that have the same group aesthetic are interpreted as being linked across states. The semantics of the group aesthetic in ggplot2 is such that if it is undefined it will get calculated based on the interaction of all discrete aesthetics (sans label). If none exists, such as in our iris animation, all data will get the same group, and will thus be matched by gganimate.

library(ggplot2)
library(gganimate)
df <- read.table(text = "node intensity Lon Lat grp
                          SRC .9  40  60 1
                          SRC .9  40  60 2
                          SRC .9  40  60 3
                            TGT .89 80   40 1
                            TGT  .8 40 30 2
                            TGT .99 30     20 3", header = TRUE)
ggm <- ggplot(data = df, aes(x = Lon, y = Lat, size= intensity, colour=node, group = grp)) +
  geom_point(alpha=.5)+
  transition_states(node)+
  labs(title = "test")+ 
  shadow_wake(wake_length = 0.5)

来源：https://stackoverflow.com/questions/54503168/gganimate-showing-transition-along-some-objects

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gganimate