title: Creating a loop that deletes specific values from a row in DFs into a list
body: <p>I have a list of 6936 elements, and I want to delete all the rows that have as flow value -1 in all the data frames in the list.</p>
  <p>I made an example of how my data frame looks like inside the list</p>
  <pre class="lang-r prettyprint-override"><code>x &lt;- data.frame(
    date = c(1, 2, 3),
    month = c(1, 1, 1),
    year = c(2000, 2000, 2000),
    flow = c(32.2, -1, 23.22)
  )
  </code></pre>
  <p>Basically I want to write a loop that does this:</p>
  <pre class="lang-r prettyprint-override"><code>df &lt;- list[[1]]       
  
  a &lt;- df[df$flow != -1, ]
  </code></pre>
  <p>Thank you for your help!</p>