缺少数组键值对时删除 csv 中乱序的列数据答案

【问题标题】：Remove out of order column data in csv when array key-value pair is missing缺少数组键值对时删除 csv 中乱序的列数据
【发布时间】：2018-02-12 23:17:35
【问题描述】：

我有一个多维数组，其中一些数组缺少在其他数组中找到的键值对。当我转换为 csv（在本例中为制表符分隔）时，行中的列单元格向左移动并替换缺少的键/值。比如这个数组：

array
  (
  array("Make" => "Volvo", "Color" => "red", "Quantity" => 18),
  array("Make" => "BMW", "Color" => "blue", "Quantity" => 13),
  array("Make" => "Saab", "Quantity" => 11),
  array("Make" => "Land Rover", "Color" => "green", "Quantity" => 15)
  );

版本 1

当我使用以下代码时：

$cfilename = 'result.csv';
$data = array
  (
  array("Make" => "Volvo", "Color" => "red", "Quantity" => 18),
  array("Make" => "BMW", "Color" => "blue", "Quantity" => 13),
  array("Make" => "Saab", "Quantity" => 11),
  array("Make" => "Land Rover", "Color" => "green", "Quantity" => 15)
  );

    //below creates csv
$fp = fopen($cfilename, 'w');
$header = false;
foreach ($data as $row)
{

fputcsv($fp, $row, chr(9));
}
fclose($fp);
return;

会给我这样的输出：

Volvo      |red    | 18
BMW        |blue   | 13
Saab       |11     | 
Land Rover |green  | 15

如果我使用键标签来编写标题，我可以让列正确排列。但是在这种情况下，缺少的键/值对的单元格不是空的，而是列号打印在它的位置。

第 2 版 这段代码：

$cfilename = 'result.csv';
$data = array
  (
  array("Make" => "Volvo", "Color" => "red", "Quantity" => 18),
  array("Make" => "BMW", "Color" => "blue", "Quantity" => 13),
  array("Make" => "Saab", "Quantity" => 11),
  array("Make" => "Land Rover", "Color" => "green", "Quantity" => 15)
  );

//below creates csv
$fp = fopen($cfilename, 'w');
$header = false;
foreach ($data as $row)
{
    if (empty($header)) //creates header, chr(9) makes tab delimited
    {
        $header = array_keys($row);
        fputcsv($fp, $header, chr(9));
        $header = array_flip($header);
    }
    fputcsv($fp, array_merge($header, $row), chr(9)); //creates rows, chr(9) makes tab delimited
}
fclose($fp);
return;

结果如下：

Make       | Color | Quantity
-----------|-------|----
Volvo      |red    | 18
BMW        |blue   | 13
Saab       |1      | 11
Land Rover | green | 15

注意，“Saab”行中颜色下方的“1”。

让任何一个版本都能正常工作会很棒，如果是版本 1，没有标题，我总是可以将该行添加到制表符分隔的输出文件中。

【问题讨论】：

标签： php arrays csv multidimensional-array export-to-csv

【解决方案1】：

如果字段不存在，为什么不直接将其设置为空字符串？

$cfilename = 'result.csv';
$data = array(
    array("Make" => "Volvo", "Color" => "red", "Quantity" => 18),
    array("Make" => "BMW", "Color" => "blue", "Quantity" => 13),
    array("Make" => "Saab", "Quantity" => 11),
    array("Make" => "Land Rover", "Color" => "green", "Quantity" => 15)
);

//below creates csv
$fp = fopen($cfilename, 'w');
$header = false;
$fields = ['Make', 'Color', 'Quantity'];
foreach ($data as $row)
{
    foreach($fields as $field) {
        if (!array_key_exists($field, $row) {
            $row[$field] = '';
        }
    }
    fputcsv($fp, $row, chr(9));
}
fclose($fp);
return;

【讨论】：

【解决方案2】：

值是1，因为这是颜色键的$header 数组中的值（您在合并之前翻转了它，所以现在它不是1 => "Color"，而是"Color" => 1）。您可以做些什么来摆脱这种情况，将所有值设置为 NULL、空字符串或占位符，或者当没有值时您想要的任何值，使用 array_map()：

<?php
$cfilename = 'result.csv';
$data = array
  (
  array("Make" => "Volvo", "Color" => "red", "Quantity" => 18),
  array("Make" => "BMW", "Color" => "blue", "Quantity" => 13),
  array("Make" => "Saab", "Quantity" => 11),
  array("Make" => "Land Rover", "Color" => "green", "Quantity" => 15)
  );
echo "<pre>";
//below creates csv
$fp = fopen($cfilename, 'w');
$header = false;
foreach ($data as $row)
{
    if (empty($header)) //creates header, chr(9) makes tab delimited
    {
        $header = array_keys($row);
        fputcsv($fp, $header, chr(9));
        $header = array_flip($header);
        $header = array_map(function($header) { return "";}, $header);
    }
    // var_dump($header);
    fputcsv($fp, array_merge($header, $row), chr(9)); //creates rows, chr(9) makes tab delimited

}
fclose($fp);
return;

Demo (without saving to file, only printing to screen)

【讨论】：