重写JSON字符串 - 按值将键分组到新数组中？

问题描述：

Ok, I have a JSON string:

[{
"Name": "Title 1",
"Count1": 556,
"Count2": 5,
"Date": "2012-12-05"
}, {
"Name": "Title 2",
"Count1": 10,
"Count2": 100,
"Date": "2012-12-05"
}, {
"Name": "Title 3",
"Count1": 798,
"Count2": 11,
"Date": "2012-12-04"
}...

and I run json_decode on that, get an array, and now I want to run through that array and calculate totals for Count1 and Count2 for each date... (and the dates can go on for whatever range). What's the fastest/niftiest way of doing that?

Sort of loop through each key => val par in a foreach, and then somehow group the date keys into a new key in a new array and add the totals in there, so that I'm getting this as an output, in JSON feed at the very end, after json_encode, sorted by date:

[{
"Date": "2012-12-05"
"TotalCount1": 566,
"TotalCount2": 105,
}, {
"Date": "2012-12-04"
"TotalCount1": 798,
"TotalCount2": 11,
}...

how would I group the array values like that before sending the whole array to json_encode?

好的，我有一个JSON字符串： p>

  [{  
“名称”：“标题1”，
“计数1”：556，
“计数2”：5，
“日期”：“2012-12-05”
}，{
“名称”  ：“Title 2”，
“Count1”：10，
“Count2”：100，
“日期”：“2012-12-05”
}，{
“名称”：“标题3”  ，
“Count1”：798，
“Count2”：11，
“日期”：“2012-12-04”
} ... 
  code>  pre> 
 
  然后我运行json_decode，得到一个数组，现在我想运行该数组并为每个日期计算Count1和Count2的总数......（并且日期可以继续进行任何范围）。 最快/最快的方法是什么？ p> 
 
 
每个键的循环次数=＆gt; 在foreach中使用val par，然后以某种方式将日期键分组到新数组中的新键并在其中添加总计，这样我就可以在json_encode之后的JSON feed中将其作为输出， 按日期排序： p> 
 
 
  [{
“Date”：“2012-12-05”
“TotalCount1”：566，
“TotalCount2”：105，\  n}，{
“Date”：“2012-12-04”
“TotalCount1”：798，
“TotalCount2”：11，
} ... 
  code>  pre> \  n 
 在将整个数组发送到json_encode之前，如何对数组值进行分组？ p> 
  div>

答

I think using a $totals array indexed on your date would work here (if I understand you correctly). Something like the example below where $data is your decoded associative JSON array:

$totals = array();

foreach ($data as $row) {
    if (isset($totals[$row['Date']]) ) {

        $totals[$row['Date']]['TotalCount1']
            = $totals[$row['Date']]['TotalCount1'] + $row['Count1'];

        $totals[$row['Date']]['TotalCount2']
            = $totals[$row['Date']]['TotalCount2'] + $row['Count2'];

    } else {

        $totals[$row['Date']] = array(
             'Date' => $row['Date'],
             'TotalCount1' => $row['Count1'],
             'TotalCount2' => $row['Count2'],
        );

    }
}

答

You will want to create an output array which is keyed by Date. Looping over each of your sub-arrays (or objects if that's what you have) from JSON, test if the date key already exists and add to it, or create it.

Lastly, call array_values() on it to strip off the Date keys and make it into a plain numeric-indexed array before encoding it back to JSON.

$output = array();
foreach ($original_array as $obj) {
  // If the date key ($obj->Date) already exists in the array, add the counts...
  if (isset($output[$obj->Date])) {
    $output[$obj->Date]->Count1 += $obj->Count1;
    $output[$obj->Date]->Count2 += $obj->Count2;
  }
  // Otherwise just append this object onto the output array
  // For objects, this must be cloned, since it would be saved as a reference otherwise.
  else {
    $output[$obj->Date] = clone $obj;
  }
}

// Then strip off the Date keys from the array:
// ready to call json_encode() on again...
$output = array_values($output);

The above assumes your original json_decode() call produced stdClass objects for the array elements, rather than associative arrays.

Here's a sample...

重写JSON字符串 - 按值将键分组到新数组中？

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