file.path在文件系统中的可移植性要比paste大，因为它会自动设置适当的目录分隔符.仅将paste(或paste0)用作文件名:

file.path is more portable across file systems than paste, as it automatically sets appropriate directory separators. Use paste (or paste0) for just the filename:

pdf(file=file.path(output.dir, paste0("dates_", name, ".pdf")), 
    width=6.25,height=9,title="Breakdown Dates:")