Hello everyone,

Is there any way to use pcarrowi command dynamically? I'm trying to find a way to insert arrows into several plots to indicate the changes in the values of some variables across time. For example, I'd like to draw an arrow between the predicted values for group 1 and group 2, pre and post trial, in the graph below (not quite in a finalized format, but just an example for the moment)
. Array

I have the values of the predicted values via matrix r(b), but these values do not seem to be compatible with addplot command. For example, if I were to insert either addplot(pcarrowi 0 k[1,1] 0 k[1,2]) or addplot(pcarrowi 0 scalar(a) 0 scalar(b)) (after defining scalars as suitable values of the matrix), I get error message "invalid point." Is there any way to dynamically use addplot (specifically pcarrowi) with scalars/matrix cells, rather than specific values?

Thank you!