Question

我需要帮助才能将keys分配给PHP中的array。

我的代码是：

//First I make an array of a csv file
$file="C:\path-to-csv\file.csv";
$csv= file_get_contents($file);
$array = array_map("str_getcsv", explode("\n", $csv));

array：

//echo json_encode($array);
["0","20150717","2:57:00","1437145020","1.56084","1.56096","1.56084","1.56094","5"],
["1","20150717","2:56:00","1437144960","1.56071","1.56089","1.56071","1.56089","9"],
["2","20150717","2:55:00","1437144900","1.5607","1.5607","1.56064","1.56064","2"], //continue

从$array的结果中，我需要为特定列分配特定的key并创建新的array“$newArray”。所以，结果如下：

//$newArray should print:
"ID" :  [0, 1, 2],                      //I would like delete this value
"n"  :  [20150717, 20150717, 20150717], //I would like delete this value
"d"  :  [2:57:00, 2:56:00, 2:55:00],    //I would like delete this value
"t"  :  [1437145020, 1437144960, 1437144900], //column 4
"o"  :  [1.56084, 1.56071, 1.5607],     //column 5
"h"  :  [1.56096, 1.56089, 1.5607],     // column 6
"l"  :  [1.56084, 1.56071, 1.56064],    // column 7
"c"  :  [1.56094, 1.56089, 1.56064],    //column 8
"v"  :  [5, 9, 2]                      //column 9

我试图通过循环和一些函数（例如array_fill_keys和array_column来完成它，但我无法获得所需的结果。如果您能帮助我，我将非常感谢$array有超过1000个条目，因此优化代码执行速度非常重要，老实说超出我的知识，我没有在Google上看到任何帮助我的东西完成这个。谢谢你的时间，对不起我的语法。

Answer 1

编辑很多时候，当您无法使用array_column时，此解决方案可以使用＆lt; 5.5。

对于foreach循环，超过1000个条目似乎没那么多。

$keys = array('t','o','h','l','c','v');    
$newArray = array();

foreach ($array as $j) {
    $r = array_slice($j, 3);
    foreach ($r as $i => $v) $newArray[$keys[$i]][] = $v*1; 
}

Json编码结果将是

"t":[1437144900,1437144900,1437145020],
"o":[1.5607,1.5607,1.56084],
"h":[1.5607,1.5607,1.56096],
"l":[1.56064,1.56064,1.56084],
"c":[1.56064,1.56064,1.56094],
"v":[2,2,5]

运行包含10.000个条目的数组

0.020426

您可以在PhpFiddle上自行测试。

Answer 2

如果您使用的是PHP 5.5，则可以使用array_column：

$newArray = array(
    't' => array_column($array, 3),
    'o' => array_column($array, 4),
    'h' => array_column($array, 4),
    ...
);

如果你使用的是较旧的PHP，你可以在Is there a function to extract a 'column' from an array in PHP?找到它的PHP实现

PHP数组集键

2 个答案: