text: user12686: In the following article:
  
  a fast and efficient Cα-based method for accurately assigning protein secondary structure elements
  
  What are the minimum and maximum cutoff distances in this algorithm?
  Also, what does it mean by:
  
  
  
  I.e. where does (2x43)x3 come from?
  
  user745: The 43 features are listed in the supplementary materials on page 4. For example,
  Feature Type Atoms Involved 
  1 Distance i, i-5 
  2 Distance i, i-4 
  3 Distance i, i-3 
  4 Distance i, i-2  
  ...
  11 Angle i-1, i, i+1 
  12 Dihedral i, i+1, i+2, i+3 
  
  Are some of them; so Feature 11 is the angle between atom(i-1), atom(i), and atom(i+1). Since it says these were calculated for both the C-alphas and pseudo-centers, this gives 2 * 43. Then this is multiplied by three as mentioned in your quoted paragraph.
  These features (measurements, almost) are numbers, not booleans - so I do not think that they use distance cutoffs as such, although the random forest method is presumably learning various cutoffs and encodes those in the structure of the forest.
  
original_text: 12686: <p>In the following article:</p>
  <ul>
  <li><a href="https://pubmed.ncbi.nlm.nih.gov/24995959/" rel="nofollow noreferrer">a fast and efficient Cα-based method for accurately assigning protein secondary structure elements</a></li>
  </ul>
  <p>What are the minimum and maximum cutoff distances in this algorithm?</p>
  <p>Also, what does it mean by:</p>
  <blockquote>
  <p><a href="https://i.stack.imgur.com/CWKAX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/CWKAX.png" alt="enter image description here" /></a></p>
  </blockquote>
  <p>I.e. where does (2x43)x3 come from?</p>
   745: <p>The 43 features are listed in the supplementary materials on page 4. For example,</p>
  <pre><code>Feature Type Atoms Involved 
  1 Distance i, i-5 
  2 Distance i, i-4 
  3 Distance i, i-3 
  4 Distance i, i-2  
  ...
  11 Angle i-1, i, i+1 
  12 Dihedral i, i+1, i+2, i+3 
  </code></pre>
  <p>Are some of them; so Feature 11 is the angle between atom(i-1), atom(i), and atom(i+1). Since it says these were calculated for both the C-alphas and pseudo-centers, this gives 2 * 43. Then this is multiplied by three as mentioned in your quoted paragraph.</p>
  <p>These features (measurements, almost) are numbers, not booleans - so I do not think that they use distance cutoffs as such, although the random forest method is presumably learning various cutoffs and encodes those in the structure of the forest.</p>
  