title: i filtered out observations not equal to 0, but when i use facet wrap, it ignores it
body: <p>Is there a way to filter specifically for each graph on the grid?</p>
  <p>I do not want the chart to show empty slots, the chart shows normally when i display the plot for individal years. However, when i try to display a facet grip by year, all charts include empty spaces which i do not want. I tried using</p>
  <pre><code>which(trade$value&gt;0)
  </code></pre>
  <p>but that didnt work.</p>
  <p>Here is my plot</p>
  <pre><code>trade%&gt;%filter(countries !='World',value !=0)%&gt;%
    ggplot(aes(x='',y=value,fill=factor(countries)),color='black')+
    geom_col(width=1)+
    geom_text(aes(label=countries),position = position_stack(vjust = 0.5))+
    scale_y_continuous(labels=dollar)+
    coord_polar(theta = 'y',start=0)+
    facet_wrap(~year,ncol=3)+
    labs(fill='Countries',title = 'Dairy products imported' )
  </code></pre>
  <p><a href="https://i.stack.imgur.com/qdh2D.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qdh2D.png" alt="Facet grid" /></a></p>
  <p>It is showing those unfilled portions which i do not want for each of the charts.</p>
  <p>Sample data</p>
  <pre><code>1                     World 2010 463000
  2                    France 2010 145000
  3               New Zealand 2010 191000
  4  United States of America 2010 126000
  5                   Denmark 2010      0
  6                   Ireland 2010      0
  7       Trinidad and Tobago 2010      0
  8                     World 2011 525000
  9                    France 2011 266000
  10              New Zealand 2011 122000
  </code></pre>
  <p>it shows normally for each year while not using the facet grid
  <a href="https://i.stack.imgur.com/34DuE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/34DuE.png" alt="enter image description here" /></a></p>