title: how to remove white lines from geom_tile (heat map) using ggplot2
body: <p>I am having trouble removing the white lines between tiles in my heat map. Below is my code and picture. Has anyone encountered this before?</p>
  
  <pre><code>t &lt;- ggplot(Drug_heatmap_df_final, 
     aes(x=reorder(Drug,Total_Deaths), y=Start_Date, fill=Total_Deaths)) + 
     geom_tile() + 
     labs(title="Heatmap of Total Deaths per month by Drug", x="Drug", y="Month") + 
     theme(plot.title = element_text(hjust=.5)) +
     scale_y_date(date_breaks="1 year" , labels = date_format("%b-%Y")) +
     theme(axis.text.x = element_text(size=13)) 
  
  plot(t)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/GFxvp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GFxvp.png" alt="enter image description here"></a></p>