using lodash groupBy how to add your own keys for grouped output

Question

I have this sample data returned from an API   I m using Lodash s   groupBy to convert the data into an object I can use better  The raw data returned is this                    name    jim            color    blue            age    22                        name    Sam            color    blue            age    33                        name    eddie            color    green            age    77            I want the   groupBy function to return an object that looks like this                   color   blue           users                                   name    jim                    color    blue                    age    22                                                name    Sam                    color    blue                    age    33                                               color   green           users                                   name    eddie                    color    green                    age    77                                    Currently I m using     groupBy a  function b    return b color     which is returning this    blue          green             the groupings are correct  but I d really like to add the keys I want  color  users   is this possible using   groupBy  or some other LoDash utility

User · Answer

In 2017 do so    chain data     groupBy  color      toPairs      map item   gt    zipObject   color    users    item      value

User · Answer

another way    chain data       groupBy  color        map  users  color    gt     users  color          value

User · Answer

Highest voted answer uses Lodash   chain function which is considered a bad practice now  Why using   chain is a mistake    Here is a fewliner that approaches the problem from functional programming perspective   import tap from  lodash fp tap   import flow from  lodash fp flow   import groupBy from  lodash fp groupBy    const map   require  lodash fp map   convert    cap   false      const result   flow        groupBy  color          map  users  color    gt    color  users           tap console log        input    Where input is an array that you want to convert

User · Answer

Isn t it this simple   var result     data               groupBy x   gt  x color               map  value  key    gt    color  key  users  value                 value

User · Answer

I would suggest a different approach  using my own library you could do this in a few lines   var groupMe   sequence    groupBy pluck  color       forOwn function acc  k  v        acc push  colors  k  users  v        return acc              var result   groupMe collection     This would a be a bit difficult with lodash or Underscore because the arguments are in the opposite order order  so you d have to use   partial a lot

User · Answer

You can do it like this in Lodash 4 x   x000D   x000D  var data      x000D     name    jim   x000D     color    blue   x000D     age    22  x000D       x000D     name    Sam   x000D     color    blue   x000D     age    33  x000D       x000D     name    eddie   x000D     color    green   x000D     age    77  x000D      x000D   x000D  console log  x000D      chain data  x000D         Group the elements of Array based on  color  property x000D       groupBy  color   x000D          key  is group s name  color    value  is the array of objects x000D       map  value  key    gt     color  key  users  value     x000D       value   x000D     x000D   lt script src  https   cdnjs cloudflare com ajax libs lodash js 4 17 15 lodash min js  gt  lt  script gt  x000D   x000D   x000D      Original Answer  var result     chain data       groupBy  color        pairs        map function currentItem            return   object   zip   color    users    currentItem                value    console log result     Online Demo  Note  Lodash 4 0 onwards  the  pairs function has been renamed to   toPairs

User · Answer

Here is an updated version using lodash 4 and ES6   const result     chain data       groupBy  color        toPairs        map pair   gt    zipObject   color    users    pair        value

User · Answer

Example groupBy and sum of a column using Lodash 4 17 4      var data                       name    jim                    color    blue                    amount   22                                       name    Sam                    color    blue                    amount   33                                      name    eddie                   color    green                   amount   77                          var result     data                      groupBy x   gt  x color                      map  value  key    gt                        color  key                      totalamount    sumBy value  amount                        users  value    value                         console log result

User · Answer

Thanks  thefourtheye  your code greatly helped   I created a generic function from your solution using the version 4 5 0 of Lodash   function groupBy dataToGroupOn  fieldNameToGroupOn  fieldNameForGroupName  fieldNameForChildren                var result     chain dataToGroupOn                groupBy fieldNameToGroupOn                toPairs                 map function  currentItem                     return   zipObject  fieldNameForGroupName  fieldNameForChildren   currentItem                                 value                return result              To use it   var result   groupBy data   color    colorId    users      Here is the updated fiddler    https   jsfiddle net sc2L9dby

[javascript] using lodash .groupBy. how to add your own keys for grouped output?

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