title: R test if a double is zero in dataframe
body: <p>How can I best test(and select) if double is "zero". If have tried this:</p>
  
  <pre><code>summary(df.1[weights==0,1])
            Min.    1st Qu.     Median       Mean    3rd Qu.       Max.       NA's 
      -100880.000      0.000      0.000      1.179      0.000   90993.000      17597 
  </code></pre>
  
  <p>But as results are non-zero - something must be wrong.</p>
  
  <p>EDIT 1
  I have ensured the colname is correct - but I still get same error:</p>
  
  <pre><code>head(df.1)
         weights
  1   0.00000
  2 -57.09428
  3   0.00000
  4   0.00000
  
      summary(df.1[weights==0,1])
                Min.    1st Qu.     Median       Mean    3rd Qu.       Max.       NA's 
          -100880.000      0.000      0.000      1.179      0.000   90993.000      17597 
  </code></pre>