[英]Group rows of data by the leading characters of a column value
我有一個如下所示的數組,我想做的是根據timestamp
列的日期子字符串創建多個子數組,例如( 2011-02-04
):
Array
(
[0] => Array
(
[avgvalue] => 0
[maxvalue] => 0
[minvalue] => 0
[nrsamples] => 0
[stddeviation] => 0
[timestamp] => 2011-02-04T11:00:00.000Z
)
[1] => Array
(
[avgvalue] => 268.3
[maxvalue] => 268.3
[minvalue] => 268.3
[nrsamples] => 0
[stddeviation] => 0
[timestamp] => 2011-02-04T12:00:00.000Z
)
[2] => Array
(
[avgvalue] => 268.391666667
[maxvalue] => 268.4
[minvalue] => 268.3
[nrsamples] => 0.0288675134595
[stddeviation] => 0.0288675134595
[timestamp] => 2011-02-04T13:00:00.000Z
)
[3] => Array
(
[avgvalue] => 268.433333333
[maxvalue] => 268.5
[minvalue] => 268.4
[nrsamples] => 0.0492365963918
[stddeviation] => 0.0492365963918
[timestamp] => 2011-02-04T14:00:00.000Z
)
[4] => Array
(
[avgvalue] => 268.5
[maxvalue] => 268.5
[minvalue] => 268.5
[nrsamples] => 0
[stddeviation] => 0
[timestamp] => 2011-02-04T15:00:00.000Z
)
[5] => Array
(
[avgvalue] => 268.575
[maxvalue] => 268.6
[minvalue] => 268.5
[nrsamples] => 0.0452267016867
[stddeviation] => 0.0452267016867
[timestamp] => 2011-02-04T16:00:00.000Z
)
[6] => Array
(
[avgvalue] => 268.616666667
[maxvalue] => 268.7
[minvalue] => 268.6
[nrsamples] => 0.0389249472081
[stddeviation] => 0.0389249472081
[timestamp] => 2011-02-04T17:00:00.000Z
)
[7] => Array
(
[avgvalue] => 268.7
[maxvalue] => 268.7
[minvalue] => 268.7
[nrsamples] => 0
[stddeviation] => 0
[timestamp] => 2011-02-04T18:00:00.000Z
)
[8] => Array
(
[avgvalue] => 268.741666667
[maxvalue] => 268.8
[minvalue] => 268.7
[nrsamples] => 0.0514928650545
[stddeviation] => 0.0514928650545
[timestamp] => 2011-02-04T19:00:00.000Z
)
[9] => Array
(
[avgvalue] => 268.8
[maxvalue] => 268.8
[minvalue] => 268.8
[nrsamples] => 0
[stddeviation] => 0
[timestamp] => 2011-02-04T20:00:00.000Z
)
[10] => Array
(
[avgvalue] => 268.883333333
[maxvalue] => 268.9
[minvalue] => 268.8
[nrsamples] => 0.0389249472081
[stddeviation] => 0.0389249472081
[timestamp] => 2011-02-04T21:00:00.000Z
)
)
上面的數組在每個子數組中都有一個時間戳鍵。 我分解了時間戳值以將日期與時間分開,現在我無法將數組拆分為子數組。
我想要的是2011-02-04
一個數組(包含該日期的所有值)和另一個2011-02-05
數組(包含所有該日期的值)。 這可以是動態的,我的意思是日期可以更多。 那么,我該怎么做呢?
我想要它:
array[0] => array(... list of all the values for 2011-02-04),
array[1] => array(...list of all values for 2011-02-05)
假設所有條目的日期格式都相同(看起來是這樣),您可以簡單地遍歷數組:
$result = array();
foreach($array as $item) {
$date = strstr($item['timestamp'], 'T', true);
if(!array_key_exists($date, $result)) {
$result[$date] = array();
}
$result[$date][] = $item;
}
參考: strstr
, array_key_exists
根據原始數組中項目的順序,您可能必須使用ksort
按時間順序對$result
數組進行排序。
在推送新的子數組之前,無需檢查數組鍵是否存在。 只需將子數組推入以日期為鍵的子數組。
解決方法很簡單:(演示)
$result = [];
foreach ($array as $row) {
$result[substr($row['timestamp'], 0, 10)][] = $row;
}
分組,如果你想組,使用排序后ksort($result)
為ASC或krsort($result)
為DESC。 如果要重新索引第一級鍵,請使用$result = array_values($result)
。
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