添加时间导出的R PDF（

Question

    pdf(file.path(vizBP,"Downed Accounts TreeMap.pdf", fsep = .Platform$file.sep), paper="special", height=8.5, width=11) 
# treemap
treemap(LCd,
        index="ND",
        vSize="ManagedDeviceCount",
        fontsize.labels=c(15), 
        overlap.labels=0.5,  
        title="Priority Downed Accounts",
        type="index"
)
dev.off()

如何在不将每个ggplot作为ca标题添加到此导出功能的情况下添加时间戳，或者在本例中我不能

添加树图