Finding the max value of an attribute in an array of objects

Question

I m looking for a really quick  clean and efficient way to get the max  y  value in the following JSON slice              x    8 11 2009        y   0 026572007               x    8 12 2009        y   0 025057454               x    8 13 2009        y   0 024530916               x    8 14 2009        y   0 031004457         Is a for-loop the only way to go about it  I m keen on somehow using Math max

User · Answer

Well  first you should parse the JSON string  so that you can easily access it s members   var arr     parseJSON str     Use the map method to extract the values   arr     map arr  function o   return o y        Then you can use the array in the max method   var highest   Math max apply this arr     Or as a one-liner   var highest   Math max apply this   map   parseJSON str   function o   return o y

User · Answer

var max   0                  jQuery map arr  function  obj      if  obj attr  gt  max      max   obj attr

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It s very simple      const array1        id  1  val  60      id  2  val  2      id  3  val  89      id  4  val  78     const array2    1 6 8 79 45 21 65 85 32 654   const max   array1 reduce  acc  item    gt  acc   acc  gt  item val   acc   item val  0   const max2   array2 reduce  acc  item    gt  acc   acc  gt  item   acc   item  0    console log max   console log max2

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ES6 solution  Math max    array map function o  return o y      For more details see https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Math max

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Or a simple sort  Keeping it real     array sort  a b   gt a y lt b y  0  y

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Here is the shortest solution  One Liner  ES6   Math max    values map o   gt  o y

User · Answer

if you  or  someone here  are free to use lodash utility library  it has a maxBy function which would be very handy in your case   hence you can use as such     maxBy jsonSlice   y

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Each array and get max value with Math   data reduce  max  b    gt  Math max max  b costo   data 0  costo

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Find the object whose property  Y  has the greatest value in an array of objects  One way would be to use Array reduce    const max   data reduce function prev  current        return  prev y  gt  current y    prev   current      returns object   https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Array Reduce http   caniuse com  search reduce  IE9 and above    If you don t need to support IE  only Edge   or can use a pre-compiler such as Babel you could use the more terse syntax   const max   data reduce  prev  current    gt   prev y  gt  current y    prev   current

User · Answer

clean and simple ES6  Babel   const maxValueOfY   Math max    arrayToSearchIn map o   gt  o y   0     The second parameter should ensure a default value if arrayToSearchIn is empty

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To find the maximum y value of the objects in array   Math max apply Math  array map function o    return o y

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Here is very simple way to go      Your DataSet   let numberArray              quot x quot    quot 8 11 2009 quot        quot y quot   0 026572007               quot x quot    quot 8 12 2009 quot        quot y quot   0 025057454               quot x quot    quot 8 13 2009 quot        quot y quot   0 024530916               quot x quot    quot 8 14 2009 quot        quot y quot   0 031004457           1  First create Array  containing all the value of Y let result   numberArray map  y    gt  y  console log result      gt  gt   0 026572007 0 025057454 0 024530916 0 031004457      2  let maxValue   Math max apply null  result  console log maxValue      gt  gt  0 031004457

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Comparison of three ONELINERS which handle minus numbers case  input in a array   var maxA   a reduce  a b   gt a y gt b y a b  y     30 chars time complexity   O n   var maxB   a sort  a b   gt b y-a y  0  y        27 chars time complexity   O nlogn              var maxC   Math max    a map o  gt o y           26 chars time complexity   gt O 2n   editable example here  Ideas from  maxA  maxB and maxC  side effect of maxB is that array a is changed because sort is in-place    x000D   x000D  var a         x   8 11 2009   y  0 026572007    x   8 12 2009   y  0 025057454           x   8 14 2009   y  0 031004457    x   8 13 2009   y  0 024530916     var maxA   a reduce  a b   gt a y gt b y a b  y  var maxC   Math max    a map o  gt o y    var maxB   a sort  a b   gt b y-a y  0  y   document body innerHTML   lt pre gt maxA    maxA  nmaxB    maxB  nmaxC    maxC  lt  pre gt    x000D   x000D   x000D   For bigger arrays the Math max    will throw exception  Maximum call stack size exceeded  Chrome 76 0 3809  Safari 12 1 2  date 2019-09-13   x000D   x000D  let a   Array 400 400  fill   x    8 11 2009    y   0 026572007          Exception  Maximum call stack size exceeded  try     let max1  Math max apply Math  a map o   gt  o y      catch e    console error  Math max apply    e message     try     let max2  Math max    a map o  gt o y      catch e    console error  Math max-map    e message    x000D   x000D   x000D   Benchmark for the 4 element array

User · Answer

I d like to explain the terse accepted answer step-by-step    x000D   x000D  var objects      x  3      x  1      x  2     x000D   x000D     array map lets you extract an array of attribute values x000D  var xValues   objects map function o    return o x      x000D     es6 x000D  xValues   Array from objects  o   gt  o x   x000D   x000D     function apply lets you expand an array argument as individual arguments x000D     So the following is equivalent to Math max 3  1  2  x000D     The first argument is  this  but since Math max doesn t need it  null is fine x000D  var xMax   Math max apply null  xValues   x000D     es6 x000D  xMax   Math max    xValues   x000D   x000D     Finally  to find the object that has the maximum x value  note that result is array   x000D  var maxXObjects   objects filter function o    return o x     xMax      x000D   x000D     Altogether x000D  xMax   Math max apply null  objects map function o    return o x       x000D  var maxXObject   objects filter function o    return o x     xMax     0   x000D     es6 x000D  xMax   Math max    Array from objects  o   gt  o x    x000D  maxXObject   objects find o   gt  o x     xMax   x000D   x000D   x000D  document write   lt p gt objects      JSON stringify objects      lt  p gt     x000D  document write   lt p gt xValues      JSON stringify xValues      lt  p gt     x000D  document write   lt p gt xMax      JSON stringify xMax      lt  p gt     x000D  document write   lt p gt maxXObjects      JSON stringify maxXObjects      lt  p gt     x000D  document write   lt p gt maxXObject      JSON stringify maxXObject      lt  p gt     x000D   x000D   x000D    Further information    Math max apply   Array prototype map   Array from   Function prototype apply   Array prototype filter   Array prototype find

[javascript] Finding the max value of an attribute in an array of objects

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