title: ROC object with pROC in R returns error (no valid data)
body: <p>I am trying to compute roc for a certain problem with R. The input I have is:</p>
  
  <p>true_values: a list of 100 1s and 0s:</p>
  
  <pre><code>true_values
      Class
  1               0
  2               1
  3               1
  4               0
  5               0
  6               0
  7               0
  8               0
  9               0
  10              0
  11              1
  </code></pre>
  
  <p>The predicted probabilities of each class, that I obtained with another program and imported from a csv. The second column corresponds to the positive class.</p>
  
  <pre><code>probs
         V1           V2
  1   0.3929680 6.070320e-01
  2   0.4335587 5.664413e-01
  3   0.8665784 1.334216e-01
  4   0.6162306 3.837694e-01
  5   0.9973085 2.691480e-03
  6   0.6845040 3.154960e-01
  7   0.6326703 3.673297e-01
  8   0.8201036 1.798964e-01
  9   0.9103053 8.969466e-02
  10  0.5736303 4.263697e-01
  11  0.9269959 7.300409e-02
  </code></pre>
  
  <p>However, when I try to compute ROC, I get the following error:</p>
  
  <pre><code> ROC &lt;- roc(true_values$Class, probs[2])
  Error in roc.default(true_values$Class, probs[2]) : 
    No valid data provided
  </code></pre>
  
  <p>Any idea why this would not be working? I checked the docs <a href="https://www.rdocumentation.org/packages/pROC/versions/1.14.0/topics/roc" rel="nofollow noreferrer">https://www.rdocumentation.org/packages/pROC/versions/1.14.0/topics/roc</a> and I believe I am using it the right way: with a response and a predictor. I have tried adding Grid=TRUE and other similar options but none are working. I have checked that my vectors are lists of numbers. What else can I try?</p>
  
  <p>Thanks!</p>