"php algorithm to generate all combinations of a specific size from a single set" Answer’s

0

I would use a recursive function. Here's a (working) example with comments. Hope this works for you!

function sampling(\$chars, \$size, \$combinations = array()) {

# if it's the first iteration, the first set
# of combinations is the same as the set of characters
if (empty(\$combinations)) {
\$combinations = \$chars;
}

# we're done if we're at size 1
if (\$size == 1) {
return \$combinations;
}

# initialise array to put new values in
\$new_combinations = array();

# loop through existing combinations and character set to create strings
foreach (\$combinations as \$combination) {
foreach (\$chars as \$char) {
\$new_combinations[] = \$combination . \$char;
}
}

# call same function again for the next iteration
return sampling(\$chars, \$size - 1, \$new_combinations);

}

// example
\$chars = array('a', 'b', 'c');
\$output = sampling(\$chars, 2);
var_dump(\$output);
/*
array(9) {
=>
string(2) "aa"
=>
string(2) "ab"
=>
string(2) "ac"
=>
string(2) "ba"
=>
string(2) "bb"
=>
string(2) "bc"
=>
string(2) "ca"
=>
string(2) "cb"
=>
string(2) "cc"
}
*/
Wednesday, March 31, 2021