取消多维数组中的数据

Question

我有 csv[ ][ ]。如何使用 for each 循环取消行中的数据设置？

for each ($index) {
if (conditions to meet) { 
unset(csv[$index]);     
}
}

Answer 1

试试这个：

foreach ($csv as $key => $value) {
        unset($csv[$key]);
    }

Answer 2

http://docs.php.net/manual/en/control-structures.foreach.php 说：

In order to be able to directly modify array elements within the loop precede $value with &. In that case the value will be assigned by reference.

这就是在使用两个 foreach 循环时修改行的单个元素时应该使用的方法。

<?php
$csv = [
    [1,2,3,4,5],
    [2,3,4,5,6],
    [3,4,5,6,7],
    [4,5,6,7,8],
];

// make $row a reference
// so that unset($row[...]) affects $csv and not only a "copy".
foreach( $csv as &$row ) { 
    foreach( $row as $key=>$column ) {
        if ( 0===$column%2 ) { // e.g. remove all even elements
            unset( $row[$key] );
        }
    }
}

var_export($csv);

打印

array (
  0 => 
  array (
    0 => 1,
    2 => 3,
    4 => 5,
  ),
  1 => 
  array (
    1 => 3,
    3 => 5,
  ),
  2 => 
  array (
    0 => 3,
    2 => 5,
    4 => 7,
  ),
  3 => 
  array (
    1 => 5,
    3 => 7,
  ),
)

或者（相同的输出）没有 foreach 循环。

<?php
$csv = [
    [1,2,3,4,5],
    [2,3,4,5,6],
    [3,4,5,6,7],
    [4,5,6,7,8],
];

$csv = array_map(
    function($row) {
        return array_filter(
            $row,
            function($col) {
                return 0!==$col%2; 
            }
        );
    },
    $csv
);

var_export($csv);

取消多维数组中的数据

Unset data in a multidimensional array

php

multidimensional-array

unset