替换数组中的一个字符串，但在php中保持其他字符串不变

Question

Say I have an array of strings like this:

$in_arr = ['a', 'a', 'b', 'b', 'a', 'b', 'b', 'a', 'a', 'b'];

I would like an efficient way to merge all a's into a single value but leave the b's untouched so the result will be:

['a', 'b', 'b', 'a', 'b', 'b', 'a', 'b']

Answer 1

With array_reduce:

$res = array_reduce($arr, function ($c, $i) {
    if ( $i!='a' || end($c)!='a' )
        $c[] = $i;
    return $c;
}, []);