Production of a BSTS Mean Absolute Percentage Error (MAPE) Plot from a Bayesian Time Series Analysis with MCMC using ggplot() and bsts() packages

See the reprex FAQ. The idea is to reduce the friction in communicating between poster and answerers. Cutting and pasting the complete code with representative data goes a long-way to reducing misunderstanding and being able to suggest solutions. It's all about getting on the same page.

Using the reprex add-in in RStudio makes it just a matter of cut-and-paste for both sides. Be sure to start with a fresh R session and make sure that the reprex throws the error of interest. Critical is representative data. It doesn't have to be all your data, or even your data at all if it behaves the same way.

If you can do that, I'm happy to work with you on getting further than just offering "that what happens when you try to cbind two data frames that don't have the same number of rows."