How do you filter out every kth element of a list with Ramda?
input = [1, 2, 3, 4, 5, 6, 7, 8, 9]
output = keepKth(input, 3)
output = [1, 4, 7]
This seemed to work:
let k = 3;
let Kth = (value, index) => (index % k == 0)
let filterKth = R.addIndex(R.filter)(Kth);
let input = [1, 2, 3, 4, 5, 6, 7, 8, 9];
let output = filterKth(input);
A variation based on Scott's comment:
const keepEvery = k => compose(pluck(0), splitEvery(k));
keepEvery(3)([1, 2, 3, 4, 5, 6, 7, 8, 9]);
//=> [1, 4, 7]
https://ramdajs.com/docs/#pluck
https://ramdajs.com/docs/#splitEvery
Probably not the cleanest, but point free.
const data = [1, 2, 3, 4, 5, 6, 7, 8, 9];
const whitelist = R.addIndex(R.reject)(R.flip(R.modulo(R.__, 3)));
console.log(
whitelist(data),
);
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.2/ramda.js" integrity="sha512-MEPRnhl9ArIiZuk6ikVrLzYxQm8ov1Ngkn4kIUO82hwpD7d+cwXQ7+isupqVgZ6HHtAEBDMff8eUhzixwEBSbA==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
And here is another method based on R.unfold. The seed is the index (initial 0), and it's incremented by k on every iteration.
const { curry, unfold } = R
const fn = curry((k, arr) => unfold(n => n < arr.length && [arr[n], n + k], 0))
const data = [1, 2, 3, 4, 5, 6, 7, 8, 9]
const result = fn(3, data)
console.log(result)
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.2/ramda.js" integrity="sha512-MEPRnhl9ArIiZuk6ikVrLzYxQm8ov1Ngkn4kIUO82hwpD7d+cwXQ7+isupqVgZ6HHtAEBDMff8eUhzixwEBSbA==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
Related
This might be something really simple, but I just can't figure it out. What I'm trying to do is take 2 arrays and filter out what I don't need and only
return the one array.
So what I have right now is this
let array1 = [1, 2, 3];
let array2 = [1, 2, 3, 4, 5, 6];
and what I would like is to return array 2 with only the items that doesn't show up in array1 so that would be 4, 5,6.
This is what I have so far
return array1.forEach(a => {
array2.filter(aa => aa !== a)
});
and that doesn't return anything
let array1 = [1, 2, 3];
let array2 = [1, 2, 3, 4, 5, 6];
let array3 = array2.filter(i => !array1.includes(i));
console.log(array3)
This might help to solve your problem.
let array1 = [1, 2, 3]
let array2 = [1, 2, 3, 4, 5, 6]
function returnList(arOne,arTwo){
return arTwo.filter(a => !arOne.includes(a))
}
let response = returnList(array1 ,array2 );
Need to pass a new Verhoeff Number every time I execute my script. The already used Verhoeff number is rejected by my application, as a business validation. Can someone help with the script for this?
The Java algorithm implementation is available at the Wikipedia page
In JMeter it's recommended to use Groovy for scripting so you will need to amend it to look like:
/**
* #see <ahref="http://en.wikipedia.org/wiki/Verhoeff_algorithm" > More Info</a>
* #see <ahref="http://en.wikipedia.org/wiki/Dihedral_group" > Dihedral Group</a>
* #see <ahref="http://mathworld.wolfram.com/DihedralGroupD5.html" > Dihedral Group Order 10</a>
* #author Colm Rice
*/
public class Verhoeff {
// The multiplication table
static int[][] d = new int[][]
{
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
[1, 2, 3, 4, 0, 6, 7, 8, 9, 5],
[2, 3, 4, 0, 1, 7, 8, 9, 5, 6],
[3, 4, 0, 1, 2, 8, 9, 5, 6, 7],
[4, 0, 1, 2, 3, 9, 5, 6, 7, 8],
[5, 9, 8, 7, 6, 0, 4, 3, 2, 1],
[6, 5, 9, 8, 7, 1, 0, 4, 3, 2],
[7, 6, 5, 9, 8, 2, 1, 0, 4, 3],
[8, 7, 6, 5, 9, 3, 2, 1, 0, 4],
[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
};
// The permutation table
static int[][] p = new int[][]
{
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
[1, 5, 7, 6, 2, 8, 3, 0, 9, 4],
[5, 8, 0, 3, 7, 9, 6, 1, 4, 2],
[8, 9, 1, 6, 0, 4, 3, 5, 2, 7],
[9, 4, 5, 3, 1, 2, 6, 8, 7, 0],
[4, 2, 8, 6, 5, 7, 3, 9, 0, 1],
[2, 7, 9, 3, 8, 0, 6, 4, 1, 5],
[7, 0, 4, 6, 9, 1, 3, 2, 5, 8]
};
// The inverse table
static int[] inv = [0, 4, 3, 2, 1, 5, 6, 7, 8, 9];
/*
* For a given number generates a Verhoeff digit
*
*/
public static String generateVerhoeff(String num) {
int c = 0;
int[] myArray = stringToReversedIntArray(num);
for (int i = 0; i < myArray.length; i++) {
c = d[c][p[((i + 1) % 8)][myArray[i]]];
}
return Integer.toString(inv[c]);
}
/*
* Validates that an entered number is Verhoeff compliant.
* NB: Make sure the check digit is the last one.
*/
public static boolean validateVerhoeff(String num) {
int c = 0;
int[] myArray = stringToReversedIntArray(num);
for (int i = 0; i < myArray.length; i++) {
c = d[c][p[(i % 8)][myArray[i]]];
}
return (c == 0);
}
/*
* Converts a string to a reversed integer array.
*/
private static int[] stringToReversedIntArray(String num) {
int[] myArray = new int[num.length()];
for (int i = 0; i < num.length(); i++) {
myArray[i] = Integer.parseInt(num.substring(i, i + 1));
}
myArray = reverse(myArray);
return myArray;
}
/*
* Reverses an int array
*/
private static int[] reverse(int[] myArray) {
int[] reversed = new int[myArray.length];
for (int i = 0; i < myArray.length; i++) {
reversed[i] = myArray[myArray.length - (i + 1)];
}
return reversed;
}
}
and in order to call this and to store the result into a JMeter Variable you need to use vars shorthand to JMeterVariables class instance, something like:
vars.put('myVar', Verhoeff.generateVerhoeff("your-source-number-here"))
and then you will be able to refer the generated value as ${myVar} where required.
I want to create a subset of my data by applying tf.data.Dataset filter operation. I have this data:
data = tf.convert_to_tensor([[1, 2, 1, 1, 5, 5, 9, 12], [1, 2, 3, 8, 4, 5, 9, 12]])
dataset = tf.data.Dataset.from_tensor_slices(data)
I want to retrieve a subset of 'dataset' which corresponds to all elements whose first column is equal to 1. So, result should be:
[[1, 1, 1], [1, 3, 8]] # dtype : dataset
I tried this:
subset = dataset.filter(lambda x: tf.equal(x[0], 1))
But I don't get the correct result, since it sends me back x[0]
Someone to help me ?
I finally resolved it:
a = tf.convert_to_tensor([1, 2, 1, 1, 5, 5, 9, 12])
b = tf.convert_to_tensor([1, 2, 3, 8, 4, 5, 9, 12])
data_set = tf.data.Dataset.from_tensor_slices((a, b))
subset = data_set.filter(lambda x, y: tf.equal(x, 1))
I need help. I trying make array only with odd numbers but I don't want use arraylist because I only want array.
Input array like this: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
I am trying to get odd only array like : [1, 3, 5, 7, 9]
val array = arrayOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
val arraylist = arrayListOf<Int>()
for(i in 0..array.size - 1) {
if(array[i] % 2 != 0)
arraylist.add(array[i])
}
val oddarray = arraylist.toArray()
Why not just use filter:
import java.util.Arrays;
fun main(args: Array<String>) {
val numbersArray = arrayOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
val oddArray = numbersArray.filter{ it % 2 != 0 }.toTypedArray()
print(Arrays.toString(oddArray)) // [1, 3, 5, 7, 9]
}
I started learning C some weeks ago and today I started learning Swift. The code is the following:
import Foundation
let interestingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 8, 16, 25],
]
var largest = 0;
for (kind, numbers) in interestingNumbers {
for number in numbers {
if number > largest {
largest = number;
}
}
}
println(largest);
Why do I need kind in the for-in thingy? For "Prime", "Square", ..., right? Can I work with that somehow, too?
“Add another variable to keep track of which kind of number was the largest, as well as what that largest number was.”
How do I build that in?
import Foundation
var largest = 0;
var largestKind: String?;
let interestingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 8, 16, 25],
]
for (kind, numbers) in interestingNumbers {
for number in numbers {
if number > largest {
largest = number;
largestKind = kind;
}
}
}
println("The number \(largest) is from the type \(largestKind)");
That's my solution at the moment. However, the output is
The number 25 is from the type Optional("Square")
How do I get rid of the 'Optional("")? I just want the word Square. I tried removing the question mark (var largestKind: String?; to var largestKind: String;) but I get an error doing that.
For those who have the same question, this is another solution I've found. var largestKind is still optional because of String? but the exclamation mark at the end \(largestKind!) makes it possible to access the value without having that optional stuff around the actual content.
import Foundation
var largest = 0;
var largestKind: String?;
let interestingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 8, 16, 25],
]
for (kind, numbers) in interestingNumbers {
for number in numbers {
if number > largest {
largest = number;
largestKind = kind;
}
}
}
println("The number \(largest) is from the type \(largestKind!).");