Lodash or JS GroupBy and Count for array of arrays

Question

I have a input :

results = [
    [ "Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS1", "small", "SW192EZ", "undefined" ],
    [ "Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "large", "SW192EZ", "undefined" ],
    [ "Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "large", "SW192EZ", "undefined" ],
    [ "Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "medium", "SW192EZ", "undefined" ],
]

I want the output to be something like

small
  DryKISS1 : 1
medium
  DryKISS2 : 1
large
  DryKISS1 : 5
  DryKISS2 : 2
  DryKISS3 : 1

Basically grouping by size and then summing a company name in the same size bracket.

I have been playing with the below, but get lost as most of the examples are for hashes / objects

console.log _.chain( results ).groupBy( 4 ).map( ( value, key ) ->
  [
    key
    _.reduce( value, ( ( result, currentObject ) ->
      {
        company: result[ 3 ]
      }
    ))
  ]
).value()

Any help appreciated

Answer 1

Group by the 4th column, then use transform to count the items by the 3rd column:

 var data = [ ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS1", "small", "SW192EZ", "undefined"], ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "large", "SW192EZ", "undefined"], ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "large", "SW192EZ", "undefined"], ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "medium", "SW192EZ", "undefined"], ]; var result = _(data) .groupBy(4) .transform(function(result, items, key) { result[key] = _.countBy(items, 3); }) .value(); console.log(result); 

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Answer 2

In plain Javascript, you could use an object with nested properties for the count.

 var results = [["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS1", "small", "SW192EZ", "undefined"], ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "large", "SW192EZ", "undefined"], ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "large", "SW192EZ", "undefined"], ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "medium", "SW192EZ", "undefined"]], grouped = {}; results.forEach(function (a) { grouped[a[4]] = grouped[a[4]] || {}; grouped[a[4]][a[3]] = (grouped[a[4]][a[3]] || 0) + 1; }); console.log(grouped); 

With max count

 var results = [["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS1", "small", "SW192EZ", "undefined"], ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "large", "SW192EZ", "undefined"], ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "large", "SW192EZ", "undefined"], ["Mon Nov 14 08:08:14 GMT+07:00 2016", "Ian Warner", "ian.warner@drykiss.com", "DryKISS2", "medium", "SW192EZ", "undefined"]], grouped = {}, max = { count: 0, keys: [] }; results.forEach(function (a) { grouped[a[4]] = grouped[a[4]] || {}; grouped[a[4]][a[3]] = (grouped[a[4]][a[3]] || 0) + 1; if (grouped[a[4]][a[3]] > max.count) { max = { count: grouped[a[4]][a[3]], keys: [{ size: a[4], group: a[3] }] }; return; } if (grouped[a[4]][a[3]] === max.count) { max.keys.push = { size: a[4], group: a[3] }; } }); console.log(max); console.log(grouped); 

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