CODEWITHSUNDEEP
javascriptarraysobjectflip
Florian
Florian

Reputation: 125

Efficient way to swap property values in array of objects

Assume we have the following array of Objects (the real has 71000 elements, but 4 objects are enough to give you an idea): 

[
    {
        source: "France"
        target: "Morocco"
        timeN: "2008"
        valueN: "252.35"
    },
    {
        source: "France"
        target: "Morocco"
        timeN: "2009"
        valueN: "424.12"
    },
    {
        source: "France"
        target: "Morocco"
        timeN: "2010"
        valueN: "152.24"
    },
    {
        source: "France"
        target: "Morocco"
        timeN: "2011"
        valueN: "-342.19"
    }
]

How can I efficiently swap source and target values on the last object, if valueN is negative? I would like to just multiply valueN with -1 or call Math.abs() and then change also source to "Morocco" and target to "France".

Update

Although all answers are great and I have taken the clean one by @Nina Scholz. However, the one from @Emil S. Jørgensen is the most performant one, once tracking the execution time. I don't know why but it seems to be most performant if you do not convert it back to a string, the valueN.

Upvotes: 2

Views: 1047

Answers (4)

Nina Scholz
Nina Scholz

Reputation: 386624

Iterate. Check. Swap. Update.

var array = [{ source: "France", target: "Morocco", timeN: "2008", valueN: "252.35" }, { source: "France", target: "Morocco", timeN: "2009", valueN: "424.12" }, { source: "France", target: "Morocco", timeN: "2010", valueN: "152.24" }, { source: "France", target: "Morocco", timeN: "2011", valueN: "-342.19" }];

array.forEach(o => {
    if (o.valueN < 0) {
        [o.source, o.target] = [o.target, o.source];
        o.valueN *= -1;
    }
});

console.log(array);
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 2

Isaac
Isaac

Reputation: 12874

array.forEach(x=> {
  if(x.valueN < 0){
    [x.source, x.target] = [x.target, x.source] //swapping values between two var
    x.valueN *= -1;
  }
});

You can try the above code. Loop thru the array and if found negative values, swap the variable and negate the valueN

Upvotes: 1

Emil S. J&#248;rgensen
Emil S. J&#248;rgensen

Reputation: 6366

Mapping the array with a call to parseFloat and Math.abs seems the simplest solution:

var data = [{
    source: "France",
    target: "Morocco",
    timeN: "2008",
    valueN: "252.35"
  },
  {
    source: "France",
    target: "Morocco",
    timeN: "2009",
    valueN: "424.12"
  },
  {
    source: "France",
    target: "Morocco",
    timeN: "2010",
    valueN: "152.24"
  },
  {
    source: "France",
    target: "Morocco",
    timeN: "2011",
    valueN: "-342.19"
  }
];
//Fix data by remapping values
data.forEach(function (entry) {
    var floatingValue = parseFloat(entry.valueN);
    entry.valueN = Math.abs(floatingValue);
    if (floatingValue < 0) {
        //Flipping
        var temp = entry.source;
        entry.source = entry.target;
        entry.target = temp;
    }
});
console.log(data);

Upvotes: 2

Willem van der Veen
Willem van der Veen

Reputation: 36620

Here is a solution that works:

let arr = [
    {
        source: "France",
        target: "Morocco",
        timeN: "2008",
        valueN: "252.35"
    },
    {
        source: "France",
        target: "Morocco",
        timeN: "2009",
        valueN: "424.12"
    },
    {
        source: "France",
        target: "Morocco",
        timeN: "2010",
        valueN: "152.24"
    },
    {
        source: "France",
        target: "Morocco",
        timeN: "2011",
        valueN: "-342.19"
    }
]



for (let el of arr) {


	if(parseInt(el.valueN) > 0) {
  	continue;
	}
  
  let source = el.source;
  let target = el.target;
  
  el.target = source;
  el.source = target;
  
  el.valueN = (el.valueN * -1).toString();
}

console.log(arr);

Hopefully you find this helpful. If you do not understand a specific part you can further ask me about it.

Upvotes: 1

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