在php foreach中按日期对数组项进行分组
我在php中有如下数组:在php foreach中按日期对数组项进行分组,php,arrays,date,foreach,grouping,Php,Arrays,Date,Foreach,Grouping,我在php中有如下数组: Array ( [0] => Array ( [id] => 1 [time] => 2014-11-09T16:32:05 [power] => 0.123 ) [1] => Array ( [id] => 2 [time] => 2014-11
Array
(
[0] => Array
(
[id] => 1
[time] => 2014-11-09T16:32:05
[power] => 0.123
)
[1] => Array
(
[id] => 2
[time] => 2014-11-19T18:32:06
[power] => 0.208
)
[2] => Array
(
[id] => 3
[time] => 2013-09-19T20:32:07
[power] => 0.106
)
[3] => Array
(
[id] => 4
[time] => 2013-09-20T10:32:07
[power] => 0.248
)
[4] => Array
(
[id] => 5
[time] => 2013-09-20T12:32:07
[power] => 0.298
)
)
我想计算由以下算法得出的每日电力消耗量:
for(i = 0; i < array.lengh - 1; i++){
$power = array.data[i].power;
$time_diff = (array.data[i+1].time)/(1000*60*60) - array.data[i].time)/(1000*60*60));
$consumption .= $power * $time_diff;
}
(i=0;i
$power=array.data[i].power;
$time_diff=(array.data[i+1].time)/(1000*60*60)-array.data[i].time)/(1000*60*60));
$consumpion.=$power*$time_diff;
}
如何在php中实现这一点,将每天的
$consumption
分组 您可以在这里使用PHP的强大功能。这将为您提供一个unix时间戳,您可以更好地使用它。要回答您的问题,可以采用以下方法
$sortedData = array();
foreach ($data as $element) {
$timestamp = strtotime($element['time']);
$date = date("d.m.Y", $timestamp); //truncate hours:minutes:seconds
if ( ! isSet($sortedData[$date]) ) { //first entry of that day
$sortedData[$date] = array($element);
} else { //just push current element onto existing array
$sortedData[$date][] = $element
}
}
这将以
Array(
['19.09.2013'] => Array(
[0] => Array([id] => ..., [time] => ..., [power] => ...),
[1] => Array([id] => ..., [time] => ..., [power] => ...),
...
),
['20.09.2013'] => Array(
[0] => Array([id] => ..., [time] => ..., [power] => ...),
[1] => Array([id] => ..., [time] => ..., [power] => ...),
...
),
...
)
为了得到总的能量,只要做如下的事情
foreach ($sortedData as $date=>$elements) {
$sum = 0;
foreach ($elements as $element) {
$sum += $element['power'];
}
echo "The total sum for $date is $sum.";
}
这些数据来自数据库吗?如果是,为什么不在那里进行计算呢?不,它们来自此格式的json文件!不应该
$date=date(“d.m.Y”)代码>be$date=date(“d.m.Y”,时间戳为$timestamp)代码>?非常感谢!代码是有效的,但问题是它不计算消耗,而是计算功率的汇总。为了计算消耗量,数组值之间的时间差必须乘以循环每一步的功率!有什么想法吗?坦斯克!!“数组值之间的时间差”?不清楚。每天第一次和最后一次记录之间的差异?或数组的每个连续元素之间的差异?。。。我很困惑是的,我的意思是->数组中每个连续元素之间的差异。是的,我的意思是->数组中每个连续元素之间的差异。