Question 171803 in Javascript Question posted in
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Can a varying-length if-else statement be converted to a for loop in Javascript?

I have the following code which includes a varying number (nk) of if-else conditions.

var n = 128; // n is 128 or greater.
var nk = 4; // nk is varying, can be 4,6,8,12,16 etc. smaller than n.

for (let i = 1; i <= n; i++) {
    if ((i < 1 * n / nk) { ... }
    else if (i < 2 * n / nk) { ... }
    else if (i < 3 * n / nk) { ... }
    else if (i < 4 * n / nk) { ... }
}

Is it possible to turn the if-else statements into a for loop (or anything else) so that it can work with varying nk? Right now, to account for varying nk values, I have to write multiple for loops with if-else statements.

I tried the following, which obviously does not work:

for (let i = 1; i < nk; i++) {
    if (x < i * n / nk)) { /* code here is a function of i */ }
}
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3

Answers


  1. Chosen as BEST ANSWER
    0

    After further trial and error, I reached the following solution, which works as I needed. The key point was to use closed interval check inside if; and use of break for better performance:

    n = 128;
var nk = 4;

for (let i = 1; i <= n; i++) {
    let nkk = n / nk;

    for (let k = 0; k < nk; k++) {
        if (i > k * nkk && i <= (k + 1) * nkk) {
            // ...
            break;
        }
    }
}

    Apologies for not properly expressing my question, this question may either be closed or kept if the answer might be useful to anyone else in the future.


  2. 0

    Yes, it is possible to convert the varying-length if-else statement into a for loop. However, you need to modify the loop condition and the if condition to accommodate the varying nk value

    var x, n; // defined before
var nk = 4;

for (let i = 0; i < nk; i++) {
    if (i === nk - 1 || x < (i + 1) * n / nk) {
        // Code here is a function of i
        break;
    }
}
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  3. 0

    Calculate the value of i as indicated in @tevemadar s comment, then perform your function of i

    const i = Math.floor(x/(n*nk));
myFunctionOfI(i);
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