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Cartesian product of multiple arrays in JavaScript
...aScript, no lodash, underscore or other libraries:
let f = (a, b) => [].concat(...a.map(a => b.map(b => [].concat(a, b))));
let cartesian = (a, b, ...c) => b ? cartesian(f(a, b), ...c) : a;
Update:
This is the same as above but improved to strictly follow the Airbnb JavaScript Style Gui...
push multiple elements to array
...
@BluE if you want to merge two arrays just use array.concat()
– Florent Arlandis
Feb 26 at 16:45
...
How to merge two arrays in JavaScript and de-duplicate items
... just merge the arrays (without removing duplicates)
ES5 version use Array.concat:
var array1 = ["Vijendra", "Singh"];
var array2 = ["Singh", "Shakya"];
console.log(array1.concat(array2));
ES6 version use destructuring
const array1 = ["Vijendra","Singh"];
const array2 = ["Singh", "Shakya"...
What is the most efficient way to concatenate N arrays?
What is the most efficient way to concatenate N arrays of objects in JavaScript?
20 Answers
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Comparing strings with == which are declared final in Java
... question about strings in Java. The following segment of simple code just concatenates two strings and then compares them with == .
...
How to skip over an element in .map()?
...urce and returns something that looks like the accumulator
// 1. create a concat reducing function that can be passed into `reduce`
const concat = (acc, input) => acc.concat([input])
// note that [1,2,3].reduce(concat, []) would return [1,2,3]
// transforming your reducing function by mapping
...
Permutations in JavaScript?
... arr.splice(i, 1);
if (arr.length === 0) {
results.push(memo.concat(cur));
}
permute(arr.slice(), memo.concat(cur));
arr.splice(i, 0, cur[0]);
}
return results;
}
return permute(inputArr);
}
Adding an ES6 (2015) version. Also does not mutate the origin...
Using LIMIT within GROUP BY to get N results per group?
...
You could use GROUP_CONCAT aggregated function to get all years into a single column, grouped by id and ordered by rate:
SELECT id, GROUP_CONCAT(year ORDER BY rate DESC) grouped_year
FROM yourtable
GROUP BY id
Result:
-----------------...
How to plot two histograms together in R?
....frame(length = rnorm(100000, 6, 2))
cukes <- data.frame(length = rnorm(50000, 7, 2.5))
# Now, combine your two dataframes into one.
# First make a new column in each that will be
# a variable to identify where they came from later.
carrots$veg <- 'carrot'
cukes$veg <- 'cuke'
# and com...
IEnumerable to string [duplicate]
...
You can use String.Concat().
var allowedString = String.Concat(
inputString.Where(c => allowedChars.Contains(c))
);
Caveat: This approach will have some performance implications. String.Concat doesn't special case collections of char...