title: Plot scatter plot on top of heatmap
body: <p>I would like to plot a scatter plot onto a heatmap.I made each type of plot with ggplot.</p>
  
  <p>Scatter plot:</p>
  
  <pre><code>lambir_t &lt;- ggplot(l_tree, aes(x=xcoord, 
  [![enter image description here][1]][1]y=ycoord))+geom_point(col='red')+xlim(c(0, 1040))+ylim(c(0, 500))
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/UZ1ry.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UZ1ry.png" alt="enter image description here"></a></p>
  
  <p>Heat map:</p>
  
  <pre><code>lambir_p &lt;- ggplot(dfo, aes(x,y,
  fillz))+geom_tile(color='white')+scale_fill_gradient(low='white', 
  high='blue')+labs(x='x', y='y', title='Lambir Hills', 
  fill='Phosphorus')
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/vHuIN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vHuIN.png" alt="enter image description here"></a></p>
  
  <p>Now I'd like to lay the scatter plot on top of the heat map so that I can see how those points vary with phosphorus concentration. Any ideas on how I can do this?</p>
  
  <p><strong>EDIT:</strong>
  <a href="https://i.stack.imgur.com/bjdmB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bjdmB.png" alt="enter image description here"></a></p>
  
  <p>The solution from @phalteman worked. This is what I got. I'm having trouble adjusting the size of the points (it looks the same when set to 1 or 100), but otherwise this is exactly what I was looking for.</p>