title: How to combine different barplot in R?
body: <p>I am a new R user.</p>
  
  <p>I have a difficult time figuring out how to combine different barplot into one graph.</p>
  
  <p>For example, </p>
  
  <p>Suppose, the top five of professions in China, are, government employees, CEOs, Doctors, Athletes, artists, with the incomes (in dollars) respectively, 20,000,17,000,15,000,14,000,and 13,000, while the top five of professions in the US, are, doctors, athletes, artists, lawyers, teachers with the incomes (in dollars) respectively, 40,000,35,000,30,000,25,000 and 20,000.</p>
  
  <p>I want to show the differences in one graph.</p>
  
  <p>How am I supposed to do that? Beware that they have different names.</p>