@Override
    public int countMissing() {
        int count = 0;
        for (int i = 0; i < size(); i++) {
            if (isMissing(i)) {
                count++;
            }
        }
        return count;
    }
@ Override public int countMissing ( ) { int count = 0 ; for ( int i = 0 ; i < size ( ) ; i ++ ) { if ( isMissing ( i ) ) { count ++ ; } } return count ; }
Returns the count of missing values in this column