Transition (Sankey) plot with time on x axis

Question

I have a transition matrix as following:

1.  A  A  B
2.  B  C  A
3.  A  C  C

where each column represents periods,each row represents an agent and each letter represents a state. I would like a create a plot such as Sankey Diagram which shows transitions from states to states in each period. Agents' identities are not important.
So I would like to have a plot like this:

.
It seems that I can use networkD3 or googleVis packages. However since the position of each node is endogenously determined by the packages, I have no clue how to put the time aspect on X axis.

Any help or alternative visualization suggestions will be highly appreciated, Thanks a lot in advance,

You can reproduce the sample data by:

    transitiondata <- data.frame("t1"=c("A","B","A"),
                                 "t2"=c("A","C","C"),
                                 "t3"=c("B","A","C"))

Answer 1

Self-answering from the future: ggalluvial package, which is perfect for this task, was developed during that time. In order to use it, we need to provide tidy data.

Let's load the libraries we need:

library(ggplot2)
library(ggalluvial)
library(tidyr)
library(dplyr

Then need to create identifiers for the data before we convert it to tidy format. So the new data is like this:

transitiondata$id <- c("id1","id2","id3")

Convert to tidy format

transitiondata_tidy <- transitiondata %>% 
                           gather(time, state, t1,t2,t3) %>% 
                           mutate(time = as.factor(time), state = as.factor(state))

Here is how our data looks like:

   id time state
1 id1   t1     A
2 id2   t1     B
3 id3   t1     A
4 id1   t2     A
5 id2   t2     C
6 id3   t2     C
7 id1   t3     B
8 id2   t3     A
9 id3   t3     C

And ggplot2 and ggalluvial does the trick:

ggplot(transitiondata_tidy,
       aes(x = time, stratum = state, alluvium = id, fill = state, label = state)) +
  geom_stratum() +
  geom_text(stat = "stratum", size = 3) +
  geom_flow(fill = "darkgrey", color = "black")

And our transition (Sankey) plot is ready: