Problem with plotmat package
Okay, that was just my reading of the help page. I hope that I haven't added to the confusion. Jim
On Fri, Sep 17, 2021 at 10:50 AM H <agents at meddatainc.com> wrote:
On 09/15/2021 09:40 PM, Jim Lemon wrote:
Oops, your plot On Thu, Sep 16, 2021 at 11:39 AM Jim Lemon <drjimlemon at gmail.com> wrote:
Hi H,
Looking at your example and the help page, it looks to me as though
the plot is consistent with the "A" matrix:
Oz
Rain Nice
Rain 0.25 0.75
Nice 0.60 0.40
# help page
A - square coefficient matrix, specifying the links (rows=to, cols=from).
In your plot (attached):
Rain (col) goes to Rain (row) 0.25
Rain (col) goes to Nice (row) 0.6
Nice (col) goes to Nice (row) 0.4
Nice (col) goes to Rain (row) 0.75
This is a bit confusing, but it seems to do what it says it does.
Jim
On Thu, Sep 16, 2021 at 10:40 AM H <agents at meddatainc.com> wrote:
I am using plotmat 1.6.5 (part of the diagram package) in R 3.6 to plot Markov transition charts but have run into an issue that I was hoping someone could shed light on here. I did e-mail the maintainer over a month ago but have not received a reply.
The issue is that the directional arrows point in the wrong direction. A brief example:
stateNames <- c("Rain", "Nice")
Oz <- matrix(c(0.25, 0.75, 0.6, 0.4), nrow = 2, byrow = TRUE)
rownames(Oz) <- stateNames; colnames(Oz) <- stateNames
plotmat(Oz, pos = c(1, 1), lwd = 1, box.lwd = 2, cex.txt = 0.8, box.size = 0.1, box.type = "circle", box.prop = 0.5, box.col = "light yellow", arr.length = 0.2, arr.width = 0.2, self.cex = 0.4, self.shifty = 0.01, self.shiftx = 0.13, main = "")
In the above example both arrows seem to point in the direction opposite to what I expect. Has anyone encountered this and know how to fix it?
Thanks.
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I am sorry but I think you have it wrong. A transition probability matrix for the rain/nice scenario would be written: Rain, Nice Rain |0.25, 0.75| Nice |0.60, 0.40| If you sum the transition probabilities for rain or nice, they should each add to 1. Logic dictates if the only two states are rain and nice, and rain continues the next day with a probability of 0.25, nice must have a probability of 0.75. Likewise, the sum of probabilities for nice weather to change to rain, 0.6, and remain the same, 0.4 must add up to 1. I find that the arrow directions are the opposite of what I expect.