R, ggvis graphing from two data frames that both need to be grouped by -

i'm creating stacked bar graph multiple horizontal lines running through it. done in shiny app. user picks option , depending on is, there either 2 or 3 horizontal lines.

here minimal reproducible example:

df1 <- data.frame(a=as.factor(rep(1:10,2)),                    b=sample(1:5,20, replace=t),                   c=c(rep("apple",10), rep("banana",10)) ) df1 <- df1[order(df1$a, df1$c),] df2 <- data.frame(a=as.factor(rep(1:10,2)),                   i=c(rep(3,10),rep(4,10)),                   j=c(rep("red",10), rep("green",10))  )  > df1     b      c 1   1 5  apple 11  1 2 banana 2   2 3  apple 12  2 3 banana 3   3 1  apple 13  3 2 banana 4   4 3  apple 14  4 1 banana 5   5 4  apple 15  5 3 banana 6   6 4  apple 16  6 2 banana 7   7 3  apple 17  7 4 banana 8   8 5  apple 18  8 1 banana 9   9 5  apple 19  9 2 banana 10 10 1  apple 20 10 3 banana > df2         j 1   1 3   red 2   2 3   red 3   3 3   red 4   4 3   red 5   5 3   red 6   6 3   red 7   7 3   red 8   8 3   red 9   9 3   red 10 10 3   red 11 11 3   red 12  1 4 green 13  2 4 green 14  3 4 green 15  4 4 green 16  5 4 green 17  6 4 green 18  7 4 green 19  8 4 green 20  9 4 green 21 10 4 green 22 11 4 green  ggvis(data=df1, x=~a, y=~b) %>%     group_by(c) %>%     layer_bars(fill=~c) %>%     layer_paths(data=df2, x=~a, y=~i, strokewidth:=2) 

which gives me following graph (it'll different each time because of sample() ).

but don't want inverse z in middle. want 2 parallel lines grouped df2$j. i'm not sure how go 2 data frames in ggvis.

the reason have df2 in long form because user choose option create more 2 horizontal lines. don't want use if , else control that. in actual code, df1 , df2 both reactives.

thank in advance.

you can give layer_paths dataset grouped on y variable horizontal lines drawn separately each group.

to this, can use data = group_by(df2, i) instead of data = df2.

and code , plot like:

ggvis(data=df1, x=~a, y=~b) %>%     group_by(c) %>%     layer_bars(fill=~c) %>%     layer_paths(data = group_by(df2, i), x = ~a, y = ~i, strokewidth:=2)