Subtract Values within a hash array - Javascript

Question

I want to subtract two values that I have in a hash array in order to know the growth I have of the Discard Value.

My array is this:

array = 
{"SiteA": [
 {device:"SiteA", discardmax:16617331511, timeCapturedmax:"February 18, 2018 at 09:27 AM"}, 
 {device:"SiteA", discardmax:16617216094, timeCapturedmax:"February 18, 2018 at 09:22 AM"}, 
 {device:"SiteA", discardmax:16617202279, timeCapturedmax:"February 18, 2018 at 09:18 AM"},
 {device:"SiteA", discardmax:16616985649, timeCapturedmax:"February 18, 2018 at 09:12 AM"}, 
 {device:"SiteA", discardmax:16616404836, timeCapturedmax:"February 18, 2018 at 09:07 AM"},  
 {device:"SiteA", discardmax:16616368250, timeCapturedmax:"February 18, 2018 at 09:03 AM"}
], 
"SiteB": [
 {device:"SiteB", discardmax:16617331511, timeCapturedmax:"February 18, 2018 at 09:27 AM"}, 
 {device:"SiteB", discardmax:16617216094, timeCapturedmax:"February 18, 2018 at 09:22 AM"}, 
 {device:"SiteB", discardmax:16617202279, timeCapturedmax:"February 18, 2018 at 09:18 AM"},
 {device:"SiteB", discardmax:16616985649, timeCapturedmax:"February 18, 2018 at 09:12 AM"}, 
 {device:"SiteB", discardmax:16616404836, timeCapturedmax:"February 18, 2018 at 09:07 AM"},  
 {device:"SiteB", discardmax:16616368250, timeCapturedmax:"February 18, 2018 at 09:03 AM"}
]}

I want to subtract the values from 'discardmax' and get the following array.

[
 {device:"SiteA", discardmax:115417, timeCapturedmax:"February 18, 2018 at 09:27 AM"}, 
 {device:"SiteA", discardmax:13815, timeCapturedmax:"February 18, 2018 at 09:22 AM"}, 
 {device:"SiteA", discardmax:216630, timeCapturedmax:"February 18, 2018 at 09:18 AM"},
 {device:"SiteA", discardmax:580813, timeCapturedmax:"February 18, 2018 at 09:12 AM"}, 
 {device:"SiteA", discardmax:36586, timeCapturedmax:"February 18, 2018 at 09:07 AM"},
 {device:"SiteB", discardmax:115417, timeCapturedmax:"February 18, 2018 at 09:27 AM"}, 
 {device:"SiteB", discardmax:13815, timeCapturedmax:"February 18, 2018 at 09:22 AM"}, 
 {device:"SiteB", discardmax:216630, timeCapturedmax:"February 18, 2018 at 09:18 AM"},
 {device:"SiteB", discardmax:580813, timeCapturedmax:"February 18, 2018 at 09:12 AM"}, 
 {device:"SiteB", discardmax:36586, timeCapturedmax:"February 18, 2018 at 09:07 AM"}
]

In ruby I used this code but now I want to use javascript:

  keystotal = arrya.keys

  arr_sub = keystotal.map { |k|
    [k, groupedtotal[k].each_cons(2).map do |g,h|
    { devicetotal: g[:devicetotal], porttotal: g[:porttotal], device_int_stats_total: g[:device_int_stats_total], octetsrxsub: g[:octetsrxtotal]-h[:octetsrxtotal], octetstxsub: g[:octetstxtotal]-h[:octetstxtotal], time_unixsub: g[:time_unixtotal]-h[:time_unixtotal], time_unixtotal: g[:time_unixtotal], timeCapturedtotal: g[:timeCapturedtotal]}
  end
  ]
  }
  table_sub = arr_sub.map { |ts| ts[1] }

That's not valid JavaScript. Use console.log(object, null, 2) to get the data in an appropriate format. Also, it's not clear what value you want to subtract. If you know the algorithm, please explain it as text, and try and write it as code. We can help you if you have problems with the last step. — Heretic Monkey
– Heretic Monkey, Commented May 11, 2020 at 18:28

Barmar · Accepted Answer · 2020-05-11 20:30:45Z

1

Loop through the array, subtracting array[i+1].discardmax from array[i].discardmax. Create a new object that merges this into a copy of array[i].

var array = 
{"SiteA": [
 {device:"SiteA", discardmax:16617331511, timeCapturedmax:"February 18, 2018 at 09:27 AM"}, 
 {device:"SiteA", discardmax:16617216094, timeCapturedmax:"February 18, 2018 at 09:22 AM"}, 
 {device:"SiteA", discardmax:16617202279, timeCapturedmax:"February 18, 2018 at 09:18 AM"},
 {device:"SiteA", discardmax:16616985649, timeCapturedmax:"February 18, 2018 at 09:12 AM"}, 
 {device:"SiteA", discardmax:16616404836, timeCapturedmax:"February 18, 2018 at 09:07 AM"},  
 {device:"SiteA", discardmax:16616368250, timeCapturedmax:"February 18, 2018 at 09:03 AM"}
], 
"SiteB": [
 {device:"SiteB", discardmax:16617331511, timeCapturedmax:"February 18, 2018 at 09:27 AM"}, 
 {device:"SiteB", discardmax:16617216094, timeCapturedmax:"February 18, 2018 at 09:22 AM"}, 
 {device:"SiteB", discardmax:16617202279, timeCapturedmax:"February 18, 2018 at 09:18 AM"},
 {device:"SiteB", discardmax:16616985649, timeCapturedmax:"February 18, 2018 at 09:12 AM"}, 
 {device:"SiteB", discardmax:16616404836, timeCapturedmax:"February 18, 2018 at 09:07 AM"},  
 {device:"SiteB", discardmax:16616368250, timeCapturedmax:"February 18, 2018 at 09:03 AM"}
]};

var result = [];
for (var k in array) {
  var arr2 = array[k];
  for (var i = 0; i < arr2.length - 1; i++) {
    result.push({ ...arr2[i],
      discardmax: arr2[i].discardmax - arr2[i + 1].discardmax
    });
  }
}

console.log(result);

edited May 11, 2020 at 20:30

answered May 11, 2020 at 18:47

Barmar

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2 Comments

Armando Quiroga Over a year ago

Thanks, but I updated the question. Please your support.

Barmar Over a year ago

Just add another loop around it that processes the properties of the top-level object.

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