title: Inserting gaps between rows and/or columns with matshow
body: <p>I am hoping to introduce gaps between specific rows / columns in heatmap similar to R's <a href="https://cran.r-project.org/web/packages/pheatmap/index.html" rel="nofollow noreferrer">pheatmap</a> <code>gaps_row</code> or <code>gaps_col</code> argument. However, after a cursory search this feature does not appear to be available.  I have considered emulating it by creating different axes with specific sizes to emulate this behavior but getting their placement correct would be tricky.  Is there an easier way I could go about emulating this functionality?</p>
  
  <p>For example:</p>
  
  <p><a href="https://i.stack.imgur.com/qaEva.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qaEva.png" alt="pheatmap gap example"></a></p>
  
  <p>From this <a href="https://stackoverflow.com/questions/41628450/r-pheatmap-change-annotation-colors-and-prevent-graphics-window-from-popping-up">question</a></p>