title: remove layers from ggplot chart with particular layers automatically
body: <p>I would like to automatically remove the <code>geom_label</code> layers from a <code>ggplot</code> chart that have a particular label. My code is:</p>
  
  <pre><code>library(ggplot2)
  library(gginnards)
  
  df &lt;- data.frame(x=1:100, y=runif(100))
  
  gp &lt;- ggplot(df, aes(x=x, y=y)) +
        geom_point() +
        geom_label(aes(x=20, y=-Inf, label="A"), vjust = -0.2) +
        geom_label(aes(x=40, y=-Inf, label="B"), vjust = -0.2) +
        geom_label(aes(x=60, y=-Inf, label="A"), vjust = -0.2) +
        geom_label(aes(x=80, y=-Inf, label="C"), vjust = -0.2)
  
  print(gp)
  </code></pre>
  
  <p>I tried:</p>
  
  <pre><code>gp &lt;- delete_layers(gp, match_type = "GeomLabel")
  </code></pre>
  
  <p>using the <code>gginnards</code> package, but then all <code>geom_labels</code> are removed. In this example I would like to automatically remove only the <code>geom_labels</code> from the ggplot chart that have label "A", for example with something like:</p>
  
  <pre><code>gp &lt;- delete_layers(gp, match_type = "GeomLabel" &amp; label = "A")
  </code></pre>
  
  <p>Is this possible? How?</p>