如何使用默认值数组和新值数组生成数组？

Question

我有一个数组$d_visitors = array_count_values($d_visitors);

array:7 [▼
  2 => 4
  5 => 1
  8 => 2
  3 => 1
  1 => 2
  9 => 3
  0 => 2
]

我正在尝试遍历该数组 24 次，并检查键 是否匹配 ，并存储它的值。

$dv = [];
for ($i = 0; $i < 24; $i++){
    foreach ($d_visitors as $k =>$v) {
        if($i == $k ){
            $dv[$i] = $v;
        }else{
            $dv[$i] = 0;
        }
    }
}

我正在尝试打印出如下内容：

array:24 [▼
  0 => 2
  1 => 2
  2 => 4
  3 => 1
  4 => 0
  5 => 1
  6 => 0
  7 => 0
  8 => 2
  9 => 3
  10 => 0
  11 => 0
  12 => 0
  13 => 0
  14 => 0
  15 => 0
  16 => 0
  17 => 0
  18 => 0
  19 => 0
  20 => 0
  21 => 0
  22 => 0
  23 => 0
]

但我一直收到这个：

array:24 [▼
  0 => 2
  1 => 0
  2 => 0
  3 => 0
  4 => 0
  5 => 0
  6 => 0
  7 => 0
  8 => 0
  9 => 0
  10 => 0
  11 => 0
  12 => 0
  13 => 0
  14 => 0
  15 => 0
  16 => 0
  17 => 0
  18 => 0
  19 => 0
  20 => 0
  21 => 0
  22 => 0
  23 => 0
]

Answer 1

试试这个方法：

$dv = [];
for ($i = 0; $i < 24; $i++){
    $dv[$i] = 0;
    if (isset($d_visitors[$i])) {
        $dv[$i] = $d_visitors[$i];
    }
}

更简单的是：

$dv = [];
for ($i = 0; $i < 24; $i++){
    $dv[$i] = isset($d_visitors[$i])? $d_visitors[$i] : 0;
}

您的代码中的问题在第 $dv[$i] = 0; 行，因为它设置为零 $dv[$i]，之前已设置。

Answer 2

您需要使用一个 flag 变量。你的代码也是正确的。

这样试试：

$dv = [];
        $flag = 0;
        for ($i = 0; $i < 24; $i++){
            $flag = 0;
            foreach ($d_visitors as $k =>$v) {
                if($i == $k ){
                    $dv[$i] = $v;
                    $flag = 1;
                }
            }
            if($flag == 0){
                $dv[$i] = 0;
            }
        }

Answer 3

Another way of asking your process is:

How can I:

merge a default array with another array based on keys
and ksort() the result array?

While you can achieve your desired result using a foreach() loop and a condition statement on each iteration, I can show you a more concise, simple approach:

This is your new array of data: $array=[2=>4,5=>1,8=>2,3=>1,1=>2,9=>3,0=>2];

There are two ways to set up your default data array:

$defaults=[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]; // 24 elements with 0 value

or more elegantly:

$defaults=array_fill(0,24,0);

Then you only need to call array_replace() to overwrite the default values with the new values. This will keep the keys in ASC order.

var_export(array_replace($defaults,$array));

You can even nest the function calls and avoid adding variable names to the global scope like this:

$d_visitors=array_replace(array_fill(0,24,0),array_count_values($d_visitors)));

Done -- merged and ksorted.

To show some other ways that programmers might try to combine the two arrays (fruitlessly or illogically), here is a demonstration.

如何使用默认值数组和新值数组生成数组？

How to generate an array using a default values array and a new values array?

php

arrays

sorting

merge

default-value