Javascript filter array by number value

Question

I have an array like this

const allChampions = 
  [ { champion: 'Vayne', percentage:  33.33, role: 'top'     } 
  , { champion: 'Jinx',  percentage:   0,    role: 'jungle'  } 
  , { champion: 'Vayne', percentage:   0,    role: 'mid'     } 
  , { champion: 'Jinx',  percentage: 100,    role: 'bottom'  } 
  , { champion: 'Vayne', percentage:   0,    role: 'support' } 
  ]

I want to filter out the array by checking for duplicate champions. If the champion is a duplicate, I want to remove the champion with the lowest percentage.

I've tried filtering the array into a new one using this:

let sortedChampions = [];
sortedChampionsWithDuplicates.map((x) =>
    sortedChampions.filter((a) => a.champion == x.champion && a.percentage >= x.percentage).length > 0 ? null : sortedChampions.push(x)
);

But this is what the end result ends up being:

[{"champion":"Vayne","percentage":33.33,"role":"top"},{"champion":"Jinx","percentage":0,"role":"jungle"},{"champion":"Jinx","percentage":100,"role":"bottom"}]

Please show us what you have tried. SO isn't a free code writing service. The objective here is for you to post your attempts to solve your own issue and others help when they don't work as expected. See How to Ask and creating a minimal reproducible example — Sven Eberth
– Sven Eberth, Commented Jun 16, 2021 at 0:16
this is unclear, you want to create a new array with the correct values or clean up the existing array ? — Mister Jojo
– Mister Jojo, Commented Jun 16, 2021 at 0:24
I just posted what I have attempted so far. I know that I can probably solve this with some for loops and conditional statements, but I want to see if there's a cleaner way to do it. — Junior Yono
– Junior Yono, Commented Jun 16, 2021 at 0:38

patrickmedaugh · Accepted Answer · 2021-06-16 00:52:59Z

2

I'm assuming this is just a quick script for your own purposes, so something like this might work:

const removeDupes = allChampions.reduce((acc, champStats) => {
  if (acc[champStats.champion]) {
    acc[champStats.champion] = acc[champStats.champion].percentage > champStats.percentage ? acc[champStats.champion] : champStats
    return acc
  } else {
    acc[champStats.champion] = champStats
    return acc
  }
}, {})

console.log(Object.values(removeDupes))

answered Jun 16, 2021 at 0:52

patrickmedaugh

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Comments

Mister Jojo · Accepted Answer · 2021-06-16 01:14:54Z

1

you can do that...

const allChampions = 
  [ { champion: 'Vayne', percentage:  33.33, role: 'top'     } 
  , { champion: 'Jinx',  percentage:   0,    role: 'jungle'  } 
  , { champion: 'Vayne', percentage:   0,    role: 'mid'     } 
  , { champion: 'Jinx',  percentage: 100,    role: 'bottom'  } 
  , { champion: 'Vayne', percentage:   0,    role: 'support' } 
  ] 

for (let i=allChampions.length;i--;) 
  {
  let curr   = allChampions[i]
    , bigger = allChampions.find(x=>x.champion===curr.champion && x.percentage > curr.percentage)
  if (bigger) 
    allChampions.splice(i,1)
  }

console.log( allChampions )

OR, if you want to create a new array:

const allChampions = 
  [ { champion: 'Vayne', percentage:  33.33, role: 'top'     } 
  , { champion: 'Jinx',  percentage:   0,    role: 'jungle'  } 
  , { champion: 'Vayne', percentage:   0,    role: 'mid'     } 
  , { champion: 'Jinx',  percentage: 100,    role: 'bottom'  } 
  , { champion: 'Vayne', percentage:   0,    role: 'support' } 
  ] 

const sortedChampions =
  allChampions.filter( (c,_,t) =>
    !t.find( x => x.champion === c.champion 
               && x.percentage > c.percentage )
                     )
  
console.log( sortedChampions )

OR, if you doesn't want to use a find :

const allChampions = 
  [ { champion: 'Vayne', percentage:  33.33, role: 'top'     } 
  , { champion: 'Jinx',  percentage:   0,    role: 'jungle'  } 
  , { champion: 'Vayne', percentage:   0,    role: 'mid'     } 
  , { champion: 'Jinx',  percentage: 100,    role: 'bottom'  } 
  , { champion: 'Vayne', percentage:   0,    role: 'support' } 
  ] 

const result = Object.values(allChampions.reduce((acc, curr) =>
  {
  if ((acc[curr.champion]?.percentage || -1) < curr.percentage ) 
    acc[curr.champion] = curr
  return acc
  }, {})) 

console.log( result )

edited Jun 16, 2021 at 1:14

answered Jun 16, 2021 at 0:38

Mister Jojo

22.9k6 gold badges28 silver badges45 bronze badges

2 Comments

Junior Yono Over a year ago

Works great. I didn't know you could write a for loop with just two statements, I thought you needed three. Pretty cool. Thank you.

Mister Jojo Over a year ago

@JuniorYono there is 3 statements in the loop, the third one is an empty statemet

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