Reduce refers to the operation, where a array of items is reduced to a single value. Use with language tag like [c++], [google-sheets-formula]. Do NOT use alone.
Questions tagged [reduce]
3548 questions
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Stream API reduce used on ArrayList not synchronized
I am using stream API reduce to test a array list of String.
for (int i = 0; i < 100; i++)
{
Stream s1 = Stream.of("aa", "ab", "c", "ad");
Predicate predicate = t -> t.contains("a");
List strings2…
Robin Sun
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1 answer
Understanding fold and reduce functions in scheme
I have generic question about scheme and lisp. How fold and reduce functions should work?
In guile scheme using (use-modules (srfi srfi-1)) you can use this:
guile> (fold cons '() '(1 2 3 4))
> (4 3 2 1)
guile> (fold cons '(1 2 3 4) '())
> (1 2 3…
jcubic
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1 answer
How to array map instead of nested for loops
For my scenario, I need to push elements to an addresses array which contains objects. I'm working with vue.js.
My current working function is:
propagateCustomerInfo(selectedOption, id){
// Propagate addresses
this.addresses =…
Luciano
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1 answer
How to group documents by a field and list unequal values with custom reduce function with CouchDB view
I have 1000's of staff documents in CouchDB, which in a simplified format look like so:
{
"_id": "1111",
"departmentId": "dept_A",
"siteId": "SITE_1"
}
{
"_id": "2222",
"departmentId": "dept_B",
"siteId": "SITE_1"
}
{
…
Super Hans
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7 answers
Sum a negative number's digits
'Write a function named sumDigits which takes a number as input and
returns the sum of each of the number's decimal
digits.'
How can I sum the digits with the first digit being negative?
For example: sumDigits(-32); // -3 + 2 = -1;
I was able…
pasha
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4 answers
How to initialize an object variable with 2 "steps": `objectVariable[step1][step2] = result;`
Original problem:
I'm trying to create a new object, but the insert is a bit complex:
I am generating an object inside an object.
result = Object.values(window.datas).reduce( (newObj, dataRow) => {
if ( (user.user_id == dataRow.user_id) &&…
wellhellothere
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1 answer
Combine a Reduce and Map Data Structure in Javascript?
I am trying to use the reduce pattern on a Javascript Array of objects. But, instead of doing this in a single reducer, I want to be able to use a different reducer based on a condition set for each of the items in the array. So, it would look like…
svsav
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R: how to Reduce() list from replicate() to matrices binding according to lowest-level element
I have used replicate() to produce a list of n_iter elements. A minimal working example with hacked code follows. I seek to produce the same output more efficiently, perhaps with Reduce() and do.call('rbind', list).
I begin with a list of n_iter…
ironchefsakai
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How to fix reducer types definition? (TS2345)
I have function that traverse array and find most likely pairs of id and differ characters counter. Incorrect values is returning as null and after mapping function i filter all of these nulls.
export const findLikelyPairsId = (testingId: string,…
anton zlydenko
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4 answers
Creating key-value pairs with js reduce() and creating an array as the value
I am having a problem with javascript's reduce() function; I have to put arrays as the value. I can sucessfully create an array but can't add new values to it.
There's an array with words and I have to create a 'map' whose keys are the first letters…
cyberkitty
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How do I add sums per group in two-dimensional array using enumerable functions?
I have a two-dimensional array as follows:
ary = [["a", 10],["a", 20],["b", 9],["b",7],["c",12]]
I want to sum the numeric values with the same key, building a hash like:
desired_result = {"a"=>30, "b"=>16, "c"=>12}
I can use a hash with a default…
Marek Radebeul
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1 answer
Javascript .reduce Boolean Unexpected Return
Trying to create a function to check for a tall number (i.e., every digit is less than or equal to the digit to its right, such as 123, 059, etc.).
Following code is the issue:
const n = parseInt(readline());
if (n.toString().length === 1)
…
Arcaster
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2 answers
PySpark Dataframe cast two columns into new column of tuples based value of a third column
As the subject describes, I have a PySpark Dataframe that I need to cast two columns into
a new column that is a list of tuples based the value of a third column. This cast will reduce or
flatten the dataframe by a key value, product id in this…
Gary C
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3 answers
Use ES6 reduce or map to compute sums and percentages in nested objects of an Array
Apologies if the title is not particularly clear. I have made a short reproducible example below of what I'm attempting to do:
var arrayOfPeopleStats = [
person1 = {
this: { makes: 10, attempts: 15, pct: .666667 },
that: { makes: 12,…
Canovice
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Complex CouchDb View
I have the following documents in a database:
{
id: 1,
text: 'Hello I had a big grannysmith apple today and a big pear'
},
{
id: 2,
text: 'Hello I had a big apple today only'
},
{
id: 3,
text: 'Hello I had a big apple today, a big pear…
newstoall
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