Javascript sum array of objects by key

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Javascript sum array of objects by key

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Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Grouping elements in array by multiple properties is the closest match to my question as it indeed groups objects by multiple keys in an array.

Sum of the array in JavaScript

Problem is this solution doesn't sum up the properties value then remove the duplicates, it instead nests all the duplicates in a two-dimensional arrays.

Objects in this array are considered duplicates only if both their shape and color are the same. If they are, I want to respectively sum up their used and instances values then delete the duplicates. So in this example result array may only contain four combinations : square redsquare bluecircle redcircle blue.

How can I get my function to properly group the objects by shape and color? Use Array reduce with a helper object to group similar objects. For each object, check if the combined shape and color exists in the helper. If it doesn't, add to the helper using Object assign to create a copy of the object, and push to the array.

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If it does, add it's values to used and instances. If you can use ES6, you use a Map to collect the values, and then convert it back to an array by spreading the Map values :. You can use reduce to create one object of unique shape color properties and Object.

Object.keys, values, entries

I have a suggestion for you. This solution groups first data, then you can do what you want after, for example, compute data as ypur wish. Assume that we have an array of objects. Each object contains info about a person and the money that possess. We want to sum up the money for all persons with the same Nationality and with the same gender. If you want groupBy keys as per conditional fields then here is the modification for Abbes answer:.

Learn more. Group objects by multiple properties in array then sum up their values Ask Question.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time.

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Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Does anyone know of a lodash if possible too way to group an array of objects by an object key then create a new array of objects based on the grouping?

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For example, I have an array of car objects:. Timo's answer is how I would do it. However the OP also asked for the duplicate make keys to be removed.

If you wanted to go all the way:. If you wanted to do this using Underscore. In plain Javascript, you could use Array reduce with an object. It appear the original question asks how to group cars by make, but omit the make in each group. So the answer would look like this:. Notice that the source array change his elements!

Object.keys, values, entries

Notice the recordset Cars and the field Make You can use Object. Prototype version using ES6 as well. Basically this uses the reduce function to pass in an accumulator and current item, which then uses this to build your "grouped" arrays based on the passed in key. Hope this helps someone!. You can also make use of array forEach method like this:. I liked metakunfu answer, but it doesn't provide the expected output exactly.

Here's an updated that get rid of "make" in the final JSON payload. I didn't make any benchmark but I believe using a for loop would be more efficient than anything suggested in this answer as well. Learn more. How to group an array of objects by key Ask Question.If you have an array of objects that you need to sort into a certain order, you might be tempted to reach for a JavaScript library. But before you do, remember that you can do some pretty neat sorting with the native Array.

You can get a refresher on that via our extensive collection of ES6 guides. This popular article was updated in November By default, the JavaScript Array. You may be wondering why 32 comes before 5. Not logical, huh? Well, actually it is. This happens because each element in the array is first converted to a string, and "32" comes before "5" in Unicode order. To avoid this, you can create a new instance of the array to be sorted and modify that instead. This is possible using an array method that returns a copy of the array.

For example, Array. Or if you prefer a newer syntax, you can use the spread operator for the same effect:. Using Array. Thankfully, the function takes an optional compareFunction parameter, which causes the array elements to be sorted according to the return value of the compare function.

We can refactor this a little, as subtracting a from b will also give us the return value:. We can use the following compare function to sort this array of singers according to their band:.

To reverse the sorting order, you can invert the return value of the compare function:.

javascript sum array of objects by key

This function has two parameters — the key we want to sort by and the order of the results i. In the code above, the hasOwnProperty method is used to check if the specified property is defined on each object and has not been inherited via the prototype chain.

This allows the function to determine the proper way to sort the array. For example, if the value of the specified property is a stringa toUpperCase method is used to convert all its characters to uppercase, so character casing is ignored when sorting.

You can adjust the above function to accommodate other data types, and any other needs your script may have. In our example above, we want to be able to sort an array of objects, whose values are either strings or numbers.

This method returns a number indicating whether a string comes before, after, or is the same as a given string in the sort order. It enables a case-insensitive sort of an array:. You can read more about localeCompare over on MDN. So there you have it — a short introduction to sorting an array of objects using vanilla JavaScript. Learn JavaScript, including ES6, from the ground up and put your new knowledge into practice by building along with a range of projects.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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It's easy when is only one array, but I have others arrays with a different property name that I would like to sum. I decided to use gruff-bunny suggestion, so I avoid prototyping native object Array. I just did a little modification to his answer validating the array and the value to sum aren't null, this is my final implementation:.

Due to all the downsides of adding a function to the Array prototype, I am updating this answer to provide an alternative that keeps the syntax similar to the syntax originally requested in the question. I know that this question has an accepted answer but I thought I'd chip in with an alternative which uses array.

Just another take, this is what native JavaScript functions Map and Reduce were built for Map and Reduce are powerhouses in many languages. Note : by making separate smaller functions we get the ability to use them again.

I thought I'd drop my two cents on this: this is one of those operations that should always be purely functional, not relying on any external variables.

A few already gave a good answer, using reduce is the way to go here. We're making it an immutable function while we're at it. What reduce is doing here is simply this: Start with a value of 0 for the accumulator, and add the value of the current looped item to it.

I'm not sure this has been mentioned yet. But there is a lodash function for that. Snippet below where value is your attribute to sum is 'value'.

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Learn more. Better way to sum a property value in an array Ask Question. Asked 5 years, 11 months ago. Active 4 months ago. Viewed k times. You may post your Answer as an answer.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Grouping elements in array by multiple properties is the closest match to my question as it indeed groups objects by multiple keys in an array. Problem is this solution doesn't sum up the properties value then remove the duplicates, it instead nests all the duplicates in a two-dimensional arrays.

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Objects in this array are considered duplicates only if both their shape and color are the same. If they are, I want to respectively sum up their used and instances values then delete the duplicates. So in this example result array may only contain four combinations : square redsquare bluecircle redcircle blue. How can I get my function to properly group the objects by shape and color?

Use Array reduce with a helper object to group similar objects. For each object, check if the combined shape and color exists in the helper.

If it doesn't, add to the helper using Object assign to create a copy of the object, and push to the array.

javascript sum array of objects by key

If it does, add it's values to used and instances. If you can use ES6, you use a Map to collect the values, and then convert it back to an array by spreading the Map values :. You can use reduce to create one object of unique shape color properties and Object.

I have a suggestion for you. This solution groups first data, then you can do what you want after, for example, compute data as ypur wish. Assume that we have an array of objects. Each object contains info about a person and the money that possess.

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We want to sum up the money for all persons with the same Nationality and with the same gender.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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JavaScript merge array of objects by key (es6)

I have an array of objects, each with a dimensions field for storing various metrics related to the object, e. Each object may be different in terms of what metrics it has. Your thing transforms the object lots of times, which is liable to not be very efficient, if that's what you meant. The observation is that you just need to see how to do your task for two objects and the rest is just a reduce. Sign up to join this community. The best answers are voted up and rise to the top.

Home Questions Tags Users Unanswered. Sum array of objects by unique keys Ask Question. Asked 25 days ago. Active 25 days ago. Viewed 75 times. I have a solution but not sure if it's optimal. Erich Erich 5 5 bronze badges. Active Oldest Votes. Here's something that I hope is simple to read that does your task.

javascript sum array of objects by key

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javascript sum array of objects by key

Question feed.Help to translate the content of this tutorial to your language! In the previous chapter we saw methods map. These methods are generic, there is a common agreement to use them for data structures.

If we ever create a data structure of our own, we should implement them too. The first difference is that we have to call Object. Why so? The main reason is flexibility. Remember, objects are a base of all complex structures in JavaScript.

So we may have an object of our own like data that implements its own data. And we still can call Object. The second difference is that Object. Just like a for. Also, there exist a method Reflect. Objects lack many methods that exist for arrays, e. It may look difficult from the first sight, but becomes easy to understand after you use it once or twice.

We can make powerful chains of transforms this way. Write the function sumSalaries salaries that returns the sum of all salaries using Object. Open a sandbox with tests. Or, optionally, we could also get the sum using Object. Open the solution in a sandbox. We want to make this open-source project available for people all around the world.

Tutorial map. They are supported for: Map Set Array Plain objects also support similar methods, but the syntax is a bit different. Please note the distinctions compared to map for example : Map Object Call syntax map.


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