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将多个一维阵列转换为二维阵列列的最有效方法

optimization arrays php

Ty W · 技术社区 · 15 年前

当我在写 for 今天早些时候,我想一定有一个更整洁的方法来做这个…所以我想我应该问问。我简短地寻找了一个重复的问题,但没有看到任何明显的问题。

问题:

给定n个长度为m的数组,将其转换为m行x n列的2d数组

例子:

$id   = [1,5,2,8,6]
$name = [a,b,c,d,e]
$result = [[1,a],
           [5,b],
           [2,c],
           [8,d],
           [6,e]]

我的解决方案:

很直截了当,可能不是最优的,但它确实有效:

<?php
// $row is returned from a DB query
// $row['<var>'] is a comma separated string of values
$categories = array();
$ids = explode(",", $row['ids']);
$names = explode(",", $row['names']);
$titles = explode(",", $row['titles']);
for($i = 0; $i < count($ids); $i++) {
    $categories[] = array("id" => $ids[$i],
                          "name" => $names[$i],
                          "title" => $titles[$i]);
}
?>

注意:我没有把name=>value位放在规范中,但是如果有办法保持它的话,那就太棒了。

2 回复 | 直到 15 年前

anomareh 15 年前

也许这个?不确定是否更有效,但肯定更干净。

/*
Using the below data:

$row['ids'] = '1,2,3';
$row['names'] = 'a,b,c';
$row['titles'] = 'title1,title2,title3';
*/

$categories = array_map(NULL,
  explode(',', $row['ids']),
  explode(',', $row['names']),
  explode(',', $row['titles'])
);

// If you must retain keys then use instead:
$withKeys = array();

foreach ($row as $k => $v) {
    $v = explode(',', $v);

    foreach ($v as $k2 => $v2) {
        $withKeys[$k2][$k] = $v[$k2];
    }
}

print_r($categories);
print_r($withKeys);

/*
$categories:

array
  0 => 
    array
      0 => int 1
      1 => string 'a' (length=1)
      2 => string 'title1' (length=6)
...

$withKeys:

array
  0 =>
    array
      'ids' => int 1
      'names' => string 'a' (length=1)
      'titles' => string 'title1' (length=6)
...
*/

在这个页面上对4个结果做了一个简单的快速基准测试,得到了以下结果:

// Using the following data set:
$row = array(
    'ids'       =>  '1,2,3,4,5',
    'names'     =>  'abc,def,ghi,jkl,mno',
    'titles'    =>  'pqrs,tuvw,xyzA,BCDE,FGHI'
);

/*
For 10,000 iterations,

Merge, for:
0.52803611755371

Merge, func:
0.94854116439819

Merge, array_map:
0.30260396003723

Merge, foreach:
0.40261697769165
*/

Peter Bailey 15 年前

是的, array_combine()

$result = array_combine( $id, $name );

编辑

下面是我如何处理您的数据转换

function convertRow( $row )
{
  $length = null;
  $keys = array();

  foreach ( $row as $key => $value )
  {
    $row[$key] = explode( ',', $value );
    if ( !is_null( $length ) && $length != count( $row[$key] ) )
    {
      throw new Exception( 'Lengths don not match' );
    }
    $length = count( $row[$key] );

    // Cheap way to produce a singular - might break on some words
    $keys[$key] = preg_replace( "/s$/", '', $key );
  }

  $output = array();

  for ( $i = 0; $i < $length; $i++ )
  {
    foreach ( $keys as $key => $singular )
    {
      $output[$i][$singular] = $row[$key][$i];
    }
  }

  return $output;
}

和一个测试

$row = convertRow( $row );
echo '<pre>';
print_r( $row );