title: histogram for multiple variables in R
body: <p>I want to make a histogram for multiple variables. 
  I used the following code :</p>
  
  <pre><code>set.seed(2)
  dataOne &lt;- runif(10)
  dataTwo  &lt;- runif(10)
  dataThree &lt;- runif(10)
  one &lt;-  hist(dataOne, plot=FALSE)
  two  &lt;-  hist(dataTwo, plot=FALSE)
  three  &lt;- hist(dataThree, plot=FALSE)
  plot(one, xlab="Beta Values", ylab="Frequency",
       labels=TRUE, col="blue", xlim=c(0,1))
  plot(two, col='green', add=TRUE)
  plot(three, col='red', add=TRUE)
  </code></pre>
  
  <p>But the problem is that they <em>cover</em> each other, as shown below. </p>
  
  <p>I just want them to be added to each other (showing the bars over each other) i.e. not overlapping/ not covering each other.
  How can I do this ?</p>
  
  <p><a href="https://i.stack.imgur.com/yOYXq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yOYXq.png" alt="enter image description here"></a></p>