数据帧：在多个单元格中单独的ID

Question

考虑以下数据框

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="Imported Rule 1">
                    <match url="^(.*)$" ignoreCase="false" />
                    <conditions logicalGrouping="MatchAll">
                        <add input="{URL}" pattern="/admin/" ignoreCase="false" negate="true" />
                        <add input="{THE_REQUEST}" pattern="^[A-Z]{3,}\s([^.]+)\.php" />
                    </conditions>
                    <action type="Rewrite" url="rewrite.php" />
                </rule>
            </rules>
        </rewrite>

    </system.webServer>
</configuration>

我需要在单独的行中拆分以分号分隔的ID，如下所示

+----+-----+-----+---------+
| A  | B   | C   | id      |
+----+-----+-----+---------+
| A  | B   | C   | 1;2;3;4 |
+----+-----+-----+---------+

最简单的方法是什么？