How to use PHP for data visualization

Data visualization is an issue that many companies and individuals are currently paying close attention to when processing data. It can transform complex data information into intuitive and easy-to-understand charts and images, thereby helping users better understand the inherent laws and trends of the data. . As an efficient scripting language, PHP also has certain advantages in data visualization. This article will introduce how to use PHP for data visualization.

1. Understand PHP chart plug-ins

In the field of PHP data visualization, a large number of chart plug-ins can provide functions such as chart drawing, chart beautification, and chart data presentation. Common and excellent PHP chart plug-ins include: Highcharts, ECharts, Jpgraph, etc.

Highcharts is a JavaScript-based chart library developed and maintained by Highsoft. It supports a variety of chart types, such as basic line charts, column charts, graph charts, pie charts, etc. Its advantages are that it is compatible with multiple browsers, has beautiful chart display effects, and supports multiple language environments.

ECharts is a set of open source data visualization tools developed by Baidu. It has the advantages of cross-platform, dynamic interaction, and good data visualization effects. It also supports a variety of chart types, such as line charts, bar charts, line charts, pie charts, bubble charts, etc.

JPGraph is a PHP chart library specifically used to generate static image charts. It is compatible with multiple PHP versions and supports multiple data types and various advanced features, such as chart scaling, legend customization, data labels, etc. .

2. Implement chart drawing through PHP code

After selecting the appropriate PHP chart plug-in, we can call the relevant library through PHP code to achieve chart drawing. The following is an example of drawing a column chart through Highcharts:

1. Introduce the js library of Highcharts

<script src="https://cdn.jsdelivr.net/npm/highcharts@9.1.0/highcharts.js"></script>

2. Create an HTML container

<div id="container" style="min-width: 310px; height: 400px; margin: 0 auto"></div>

3. Write PHP code

<?php
// 1. 数据连接和查询
$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = '';
$dbname = 'test';
$conn = mysqli_connect($dbhost, $dbuser, $dbpass) or die ('Error connecting to mysql');
mysqli_select_db($conn, $dbname);
$sql = 'SELECT * FROM employee';
$result = mysqli_query($conn, $sql);
$data = array();
foreach ($result as $row) {
    $data[] = array($row['name'], (int)$row['salary']);
}
mysqli_close($conn);

// 2. 绘制图表
echo '
<script>
Highcharts.chart("container", {
    chart: {
        type: "column"
    },
    title: {
        text: "员工薪资情况"
    },
    xAxis: {
        type: "category"
    },
    yAxis: {
        title: {
            text: "薪资 (元)"
        }
    },
    series: [{
        name: "薪资",
        data: '.json_encode($data).'
    }]
});
</script>
';
?>

With the above PHP code, we can successfully draw a simple column chart. The chart data comes from the employee table in the MySQL database.

3. Cooperate with JavaScript to achieve dynamic interaction

In addition to drawing static charts, we usually also need to implement dynamic interactions with charts, such as clicking on the legend to display or hide certain data, or displaying it when the mouse is hovering Data details, etc. This requires the use of JavaScript and PHP code. The following uses Highcharts as an example to explain.

1. First introduce Highcharts and related JavaScript code into HTML

<script src="https://cdn.jsdelivr.net/npm/highcharts@9.1.0/highcharts.js"></script>

2. Then write PHP code and draw a simple column chart

<?php
// 数据查询和处理
$categories = array('第一季度', '第二季度', '第三季度', '第四季度');
$seriesData = array(
    array(
        'name' => '销售额',
        'data' => array(100, 120, 150, 250)
    ),
    array(
        'name' => '净利润',
        'data' => array(50, 70, 100, 150)
    )
);

// 动态交互
?>
<script>
Highcharts.chart("container", {
    chart: {
        type: "column"
    },
    title: {
        text: "销售额和净利润"
    },
    xAxis: {
        categories: <?php echo json_encode($categories); ?>
    },
    yAxis: [{
        title: {
            text: "销售额"
        }
    }, {
        title: {
            text: "净利润"
        },
        opposite: true
    }],
    series: <?php echo json_encode($seriesData); ?>
});
</script>

3. Next, write dynamic interactive events through JavaScript to display or hide the corresponding data by clicking on the legend

<script>
document.getElementById('container').addEventListener('click', function(e) {
    var chart = Highcharts.chart('container');
    if (e.target.tagName == 'tspan') {
        var seriesIndex = parseInt(e.target.parentNode.getAttribute('data-highcharts-series'));
        var series = chart.series[seriesIndex];
        if (series.visible) {
            series.hide();
        } else {
            series.show();
        }
    }
}, false);
</script>

Through the above steps, we have successfully implemented a dynamic display of a click on the legend. Or hide the column chart of data, and use JavaScript scripts to achieve dynamic interaction effects.

Summary

Data visualization aims to provide users with a more intuitive and efficient way to understand data. As a versatile and efficient programming language, PHP can use appropriate chart plug-ins and Various animation features provided in JavaScript can achieve rich and diverse data visualization effects. However, you must also pay attention to data security during use, and promptly deal with issues such as cross-site scripting attacks on charts to make data visualization more secure and reliable, and promote the efficient and intelligent development of data analysis and decision-making.

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