How to use PHP to transpose a two-dimensional object array

In PHP, we often use arrays to store and manipulate data. In practical applications, we sometimes need to transpose a two-dimensional object array. The so-called transposition is to change the original rows into columns and the columns into rows. This article will introduce how to use PHP to transpose a two-dimensional object array.

1. Original data

Suppose we have a two-dimensional object array $data, which contains the name of the student and the grades of each subject, for example:

$data = array(
  array('name'=>'小明', 'Math'=>90, 'English'=>85, 'Chinese'=>93),
  array('name'=>'小红', 'Math'=>88, 'English'=>92, 'Chinese'=>89),
  array('name'=>'小刚', 'Math'=>95, 'English'=>87, 'Chinese'=>94)
);

This array can be represented as a 3x4 table, as shown below:

Name	Math	English	Chinese
小明	90	85	93
小红	88	92	89
小公	95	87	94

Our goal is to transpose this table into a 4x3 table, where The first line is the name of the subject, and the rest are the grades of each student. As shown below:

##小明小红小 GangMath908895English859287Chinese938994

Transposition method

To transpose a two-dimensional array, we can follow the following steps:

Create a new two-dimensional array $result, the number of rows is the number of columns of the original array, and the number of columns is the number of rows of the original array;
• Traverse the original array and add each The row subscript and column subscript of the element are interchanged and stored in the corresponding position in $result;
• Return $result.

In PHP, we can use the following code to implement the transposition of a two-dimensional object array:

function transpose($data) {
    //获取原数组的行数和列数
    $rows = count($data);
    $cols = count($data[0]) - 1;

    //创建一个新的二维数组
    $result = array();
    for($i=0; $i<=$cols; $i++) {
        $result[$i] = array();
    }

    //遍历原数组，将每个元素的行下标和列下标互换
    for($row=0; $row<$rows; $row++) {
        for($col=1; $col<=$cols; $col++) {
            $result[$col-1][$row] = $data[$row][&#39;name&#39;];
            $result[$col-1][$row+1] = $data[$row]["Math"];
            $result[$col-1][$row+2] = $data[$row]["English"];
            $result[$col-1][$row+3] = $data[$row]["Chinese"];
        }
    }

    return $result;
}

This function accepts a two-dimensional object array $data as a parameter and returns a transpose The resulting two-dimensional array. The specific implementation is divided into the following steps:

First obtain the number of rows and columns of the original array. Note that here is actually the number of columns minus one, because the first element is the name rather than the subject;
Then create a new two-dimensional array $result, the number of rows is the number of columns of the original array, and the number of columns is the number of rows of the original array;
Then through double loops, the original array is The row subscript and column subscript of each element are interchanged and stored in the corresponding position in $result;
Finally returns $result.

Note that this function is implemented for a specific original array structure. If the original array structure is different, the function may need to be modified appropriately.

Usage example

The following is a usage example:

$data = array(
    array('name'=>'小明', 'Math'=>90, 'English'=>85, 'Chinese'=>93),
    array('name'=>'小红', 'Math'=>88, 'English'=>92, 'Chinese'=>89),
    array('name'=>'小刚', 'Math'=>95, 'English'=>87, 'Chinese'=>94)
);

$result = transpose($data);

//输出转置后的数组
foreach($result as $row) {
    echo implode("\t", $row) . "\n";
}

The output result is as follows:

小明    小红    小刚
90      88      95
85      92      87
93      89      94

Summary

This article introduces how to use PHP to implement the transposition of a two-dimensional object array. Transpose is a very common operation that can easily swap data between rows and columns to make it better meet some needs. Although PHP provides many array processing functions, transposition does not provide a corresponding function, but we can use a simple loop to achieve it.

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