gganimate: include additional variable other than states level variable or frame in title expression

问题:

I'd like to insert another column value of my data into a gganimate animation title.

Example, here the states level variable is x and I'd like to add to title variable y:

df <- tibble(x = 1:10, y = c('a', 'a', 'b', 'd', 'c', letters[1:5])) df  A tibble: 10 x 2        x y        <int> <chr>  1     1 a      2     2 a      3     3 b      4     4 d      5     5 c      6     6 a      7     7 b      8     8 c      9     9 d     10    10 e  

This works as expected:

ggplot(df, aes(x, x)) +   geom_point() +   labs(title = '{closest_state}') +   transition_states(x,                     transition_length = 0.1,                     state_length = 0.1) 

This fails:

ggplot(df, aes(x, x)) +   geom_point() +   labs(title = '{closest_state}, another_var: {y}') +   transition_states(x,                     transition_length = 0.1,                     state_length = 0.1) 

Error in eval(parse(text = text, keep.source = FALSE), envir) :
object 'y' not found

Also tried this, but y will not change:

ggplot(df, aes(x, x)) +   geom_point() +   labs(title = str_c('{closest_state}, another_var: ', df$y)) +   transition_states(x,                     transition_length = 0.1,                     state_length = 0.1) 

Another option is to map y as the states level variable and use the frame variable instead of x, but in my application y is either a not-necessarily-unique character variable like above, or it is a numeric variable but again not-necessarily-unique and not-necessarily-ordered. In which case gganimate (or ggplot?) will order it as it sees fit, making the final result weird not ordered by x:

ggplot(df, aes(x, x)) +   geom_point() +   labs(title = '{frame}, another_var: {closest_state}') +   transition_states(y,                     transition_length = 0.1,                     state_length = 0.1) 

So how to simply add the changing value of the un-ordered, not numeric, y variable?

Finally: This question was asked here but without a reproducible example so it was not answered, hoping this one is better.

回答1:

One dirty solution would be to paste together the variables and make a new one to use in the transition_states:

df <- mutate(df, title_var = factor(paste(x, y, sep="-"), levels = paste(x, y, sep="-"))) # # A tibble: 6 x 3 # x y     title_var # <int> <chr> <fct>     # 1     1 a     1-a       # 2     2 a     2-a       # 3     3 b     3-b       # 4     4 d     4-d       # 5     5 c     5-c       # 6     6 a     6-a   

Then we could use gsub() in ordet to strip closest_state from the unwanted part, like this:

gsub(pattern = "\\d+-", replacement = "", "1-a")  "a" 

So:

ggplot(df, aes(x, x)) +   geom_point() +   labs(title = '{gsub(pattern = "\\d+-", replacement = "", closest_state)}') +   transition_states(title_var, transition_length = 0.1, state_length = 0.1) 

回答2:

Another possibility, slightly more compact, from the author of gganimate himself, following the issue I opened:

https://github.com/thomasp85/gganimate/issues/252#issuecomment-450846868

According to Thomas:

There are multiple reasons why random columns from the input data cannot be accessed so it is unlikely to get any better than this...

文章来源: gganimate: include additional variable other than states level variable or frame in title expression