title: reduce width of bars in multiple barplot R
body: <p>I need to reduce the width of the bars in the below multiple barplot:</p>
  
  <p><a href="https://i.stack.imgur.com/AcDDE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/AcDDE.png" alt="enter image description here"></a></p>
  
  <p>I tried to use the <code>space</code> option as per here <a href="https://stackoverflow.com/questions/15750931/change-width-of-bars-in-barchart-r">Change width of bars in barchart (R)</a> but it seems that with multiple barplot (i.e. in my case 4 bars per each variable) the function <code>space</code> does not work.</p>
  
  <p>Here's some fake data that reproduce the plot:</p>
  
  <pre><code>mat_example = matrix(rnorm(40), 4, 10)
  barplot(mat_example[,c(1:10)], beside = TRUE)
  </code></pre>
  
  <p>Thank you for any suggestions.</p>