php - 在循环中获取数组的增量

Question

我在从数据库中获取数据的 while 循环中无法正确递增变量。

这是代码:

while ($row = $result->fetch_array(MYSQLI_ASSOC)) {
    //January
    if ($row['month'] ==1){
        if ($row['day_range'] == '01-07') {
            $val1_1 = $row['duration'];
            $int1_1 = $row['intensity'];
        }
        elseif ($row['day_range'] == '08-14') {
            $val1_2 = $row['duration'];
            $int1_2 = $row['intensity'];
        }
        elseif ($row['day_range'] == '15-21') {
            $val1_3 = $row['duration'];
            $int1_3 = $row['intensity'];
        }
        elseif ($row['day_range'] == '22-end') {
            $val1_4 = $row['duration'];
            $int1_4 = $row['intensity'];
        }
        //Avg intensity
        $int1 = ($int1_1 + $int1_2 + $int1_3 + $int1_4)/4;
    }
}

所以我每个月都有这个代码。
这里的问题是有时我没有 4 个值，所以最后当我计算 AVG 时它有时是错误的，因为它总是将它除以 4

我做了什么:

我想到每次我有一个值时递增一个变量 $i，就像这样

$i = 0;
while ($row = $result->fetch_array(MYSQLI_ASSOC)) {
    //January
    if ($row['month'] ==1) {
        if ($row['day_range'] == '01-07') {
            $val1_1 = $row['duration'];
            $int1_1 = $row['intensity'];
            $i++;
        }
        elseif ($row['day_range'] == '08-14') {
            $val1_2 = $row['duration'];
            $int1_2 = $row['intensity'];
            $i++;
        }
        elseif ($row['day_range'] == '15-21') {
            $val1_3 = $row['duration'];
            $int1_3 = $row['intensity'];
            $i++;
        }
        elseif ($row['day_range'] == '22-end') {
            $val1_4 = $row['duration'];
            $int1_4 = $row['intensity'];
            $i++;
        }
        //Avg intensity
        $int1 = ($int1_1 + $int1_2 + $int1_3 + $int1_4)/$i;
    }
    $i = 0;
    //code for next month
}

但它不起作用，我已经回应了它并且 $i 保持在 1。
我认为这是因为它逐行获取，所以它永远不会通过所有增量来达到所需的值。

请问我该怎么做？

Answer 1

// Here is an array to get the data of EACH month
$month = array();
$i = 0;
while ($row = $result->fetch_array(MYSQLI_ASSOC)) {
    // This way, you will have $month[1] for January, $month[2] for February, etc.
    $month[$row['month']][] = array(
        "duration" => $row['duration'],
        "intensity" => $row['intensity'];
    );
}

// Now you get all the data, you can calculate the Avg intensity for each month
foreach ($month as $month_number => $data) {
    $moy = count($month[$month_number]); // Will be 4 if you have 4 period, 3 if only 3, etc.
    $sum = 0;

    foreach ($data as $value) {
        $sum += $value['intensity'];
    }

    $month[$month_number]['avg_intensity'] = $sum / $moy;
}

使用这种方法，您应该得到一个数组，其中包含您想要的所有数据，如下所示:

$month = array(
    // January
    1 => array(
        0 => array(
            'duration' => ...,
            'intensity' => ...
        ),
        1 => array(
            'duration' => ...,
            'intensity' => ...
        ),
        ...
        'avg_intensity' => /* moy of all intensity of the month */
    ),
    // February
    2 => array(
        ...
    ),
    ...
);

希望对你有帮助!

编辑:

如果 Nigel Ren 的评论建议，你可以替换

$sum = 0;
foreach ($data as $value) {
    $sum += $value['intensity'];
}

通过

$sum = array_sum(array_column($data, "intensity"));