Round to closest list value?

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  john_mcclary Member, Developers Posts: 3,898 PRO

  May 2020

  There are a few rounding funcitons
  
  ceil() rounds up to  nearest whole number
  floor() rounds down to nearest whole number
  round() rounds to nearest up or down to nearest whole number
  roundToPrecision() will round with decimals
  
  

  var listStart = [1.9859,9.23,9.2525,11.652,0.654110111];     
          var listFloor = [];
          var listCeil = [];
          var listRound = [];
          var listRoundToPrecision = [];
          
          for (var item in listStart)
          {
              listFloor = append(listFloor, floor(item));
              listCeil = append(listCeil, ceil(item));
              listRound = append(listRound, round(item));
              listRoundToPrecision = append(listRoundToPrecision, roundToPrecision(item, 2));
          }
          
          println("Original List: " ~ listStart);
          println("Rounded List Down: " ~ listFloor);
          println("Rounded List Up: " ~ listCeil);
          println("Rounded List Nearest: " ~ listRound);
          println("Rounded List Nearest (2 place decimal): " ~ listRoundToPrecision);
  
  
  // result \\
  Original List: [ 1.9859 , 9.23 , 9.2525 , 11.652 , 0.654110111 ]
  Rounded List Down: [ 1 , 9 , 9 , 11 , 0 ]
  Rounded List Up: [ 2 , 10 , 10 , 12 , 1 ]
  Rounded List Nearest: [ 2 , 9 , 9 , 12 , 1 ]
  Rounded List Nearest (2 place decimal): [ 1.99 , 9.23 , 9.25 , 11.65 , 0.65 ]
  
  

  
  

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  konstantin_shiriazdanov Member Posts: 1,221 ✭✭✭✭✭

  May 2020 edited May 2020

  I have a function maxItem() which returns a max value of the list based on some other estimation function:

  <pre class="CodeBlock"><code>function maxItem(container is array, estimationFunction is function)<br>{<br>&nbsp;&nbsp;&nbsp; var max = container[0];<br>&nbsp;&nbsp;&nbsp; for (var item in container)<br>&nbsp;&nbsp;&nbsp; {<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if (estimationFunction(item) > estimationFunction(max))<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; max = item;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp; return max;<br>}

  say we have a value "value" and estimation function may be:

  const estFunction = function(x){return -abs(x - value)};

  then you just do this:

  const roundedItem = maxItem(roundedArr, estFunction);

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  ilya_baran Onshape Employees, Developers, HDM Posts: 1,175

  May 2020

  If your array is small, Konstantin's method works fine.  If you have a large array, the efficient method for solving this problem is binary search: https://en.wikipedia.org/wiki/Binary_search_algorithm#Procedure_for_finding_the_leftmost_element (use that procedure and then pick the closer one of A[L] and A[L-1])

  Ilya Baran \ VP, Architecture and FeatureScript \ Onshape Inc

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  Evan_Reese Member Posts: 2,064 PRO

  May 2020

  Thanks for all the info everyone!

  Evan Reese / Principal and Industrial Designer with Ovyl
  Website: ovyl.io
  

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