Why don’t the main R and Python keyring packages, r-lib/keyring and jaraco/keyring, seem to be able to read the same passwords from Windows Credential Manager on Windows 10? In short: because the R package gives the credentials a name like :service-name:user-name, while the Python package simply uses service-name (or user-name@service-name if there are multiple credentials for the same user). If you want to store credentials for user mjw for the service local-database, the best way to do that is to open Windows Credential Manager (Start > Credential Manager), click Add a generic credential, and enter:
All plots generated within an R Markdown document chunk take the width and height defined in that chunk’s options, meaning that all plots within a chunk will be the same size. There is a hacky way to get around this restriction, though.