How to Perform an Action Every 5 Results

php array and for loop - add br after 5 resultss

Use the Modulus operator.

<?php
$sm2 = array( "angry", "cool", "cry", "happy", "heart", "kiss", "mute", "sad", "smile"); 
for($j=0;$j<count($sm2); $j++) {
     if(!empty($j) && $j % 5 == 0) {
          echo '<br>';
     }
     echo $sm2[$j];
}

Output:

angrycoolcryhappyheart<br>kissmutesadsmile

Demo: https://eval.in/614166

Or with your actual code:

for($j=0;$j<count($sm2); $j++) {
    if(!empty($j) && $j % 5 == 0) {
          $data .= '<br>';
    }
    $data=$data . "<img id='". $sm2[$j] ."' src='images/emotions/" . $sm2[$j] . ".png' data-toggle='tooltip' title=". $sm2[$j] ."  width='32' height='32' style='margin:5px;'
    onclick='insertEmoticons(this.id);'/>";
}

Also note $data=$data . is the same as $data .= ....

Execute statement every N iterations in Python

How about keeping a counter and resetting it to zero when you reach the wanted number? Adding and checking equality is faster than modulo.

printcounter = 0

# Whatever a while loop is in Python
while (...):   
    ...
    if (printcounter == 1000000):
        print('Progress report...')
        printcounter = 0
    ...
    printcounter += 1

Although it's quite possible that the compiler is doing some sort of optimization like this for you already... but this may give you some peace of mind.

How to run a function multiple times and write the results to a list?

Combination of above answer, comment, and my own answer. Naturally, I like mine better. Also, I think there is a mistake in the above answer for base R.

n <- 10

# give 1 to gen_mat n-times
lapply(rep(1, n), gen_mat)

# replicate n-times 
replicate(n, gen_mat(1), simplify=FALSE)

# lapply returns error if FUN is not function or 
# the function is not taking an argument. Hence a dummy function.
lapply(seq_len(n), function(x) gen_mat(1))

microbenchmarking the three methods

I used a larger value for n, but the results are similar in my desktop with smaller n as well. For this, replicate takes longer than the other two methods.

set.seed(1)
gen_mat <- function(x) matrix(c(1, 1, 1, x + rnorm(1)), nrow = 2)
n <- 1000 

library(microbenchmark)
library(ggplot2)

mb <- microbenchmark(
  lap1 = {lapply(rep(1, n), gen_mat)},
  repl = {replicate(n, gen_mat(1), simplify=FALSE)},
  lap2 = {lapply(seq_len(n), function(x) gen_mat(1))},
  times = 10000L
)

mb
# Unit: milliseconds
# expr      min       lq     mean   median       uq      max neval cld
# lap1 2.839435 3.494157 4.806954 3.854269 5.611413 103.0111 10000  a 
# repl 3.091829 3.777199 5.140789 4.165856 6.013591 101.4318 10000   b
# lap2 3.131491 3.761274 5.089170 4.140316 5.939075 101.1983 10000   b

autoplot(mb)

flutter run function every x amount of seconds

build() can and usually will be called more than once and every time a new Timer.periodic is created.

You need to move that code out of build() like

Timer? timer;

@override
void initState() {
  super.initState();
  timer = Timer.periodic(Duration(seconds: 15), (Timer t) => checkForNewSharedLists());
}

@override
void dispose() {
  timer?.cancel();
  super.dispose();
}

Even better would be to move out such code from widgets entirely in an API layer or similar and use a StreamBuilder to have the view updated in case of updated data.

Run certain code every n seconds

import threading

def printit():
  threading.Timer(5.0, printit).start()
  print "Hello, World!"

printit()

# continue with the rest of your code

https://docs.python.org/3/library/threading.html#timer-objects

PHP: How do you determine every Nth iteration of a loop?

The easiest way is to use the modulus division operator.

if ($counter % 3 == 0) {
   echo 'image file';
}

How this works:
Modulus division returns the remainder. The remainder is always equal to 0 when you are at an even multiple.

There is one catch: 0 % 3 is equal to 0. This could result in unexpected results if your counter starts at 0.

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