🦋 生成对称列表（镜像回文列表）Create a Symmetric List

使用说明与常见问题How-to & FAQ

「生成对称列表（镜像回文列表）」是什么？What is the Create a Symmetric List tool?

把列表变成左右对称的镜像列表：A B C → A B C B A（中间项不重复）或 A B C C B A（中间成对），也可以先倒序再镜像得到 C B A B C。自动识别分隔符并按原分隔符输出。适合做来回往返的路线、动画的往返帧序、乐谱和对称图案，数据在本地处理。Turn a list into a mirror-image list: A B C → A B C B A (the middle item once) or A B C C B A (a mirrored pair in the middle), or mirror outwards from the end to get C B A B C. Separators are detected automatically and kept in the output. Handy for there-and-back routes, ping-pong animation frame orders, music patterns and symmetric designs. Processed locally.

如何使用「生成对称列表（镜像回文列表）」？How do I use the Create a Symmetric List tool?

在「生成对称列表（镜像回文列表）」中，把内容粘贴或输入到上方输入框，按需设置「输入分隔符」、「自定义」、「对称方式」，结果会实时显示在下方，点击「复制结果」即可复制。例如输入「1, 2」，得到「1, 2, 1」。In the Create a Symmetric List: Paste or type into the input box, adjust "Input separator", "Custom", "Mirror"; the result appears below instantly — click "Copy result" to copy it. Example: "1, 2" → "1, 2, 1".

四种对称方式有什么区别？How do the four mirror modes differ?

A B C B A：在最后一项处折返，中间项只出现一次，结果总是奇数项，适合往返路线和动画往返帧（不会在折返处停顿两帧）；A B C C B A：中间两项相同，结果为偶数项；后两种先把列表倒过来再镜像，以第一项为中心。A B C B A turns back at the last item so the middle appears once and the result always has an odd count — ideal for round trips and ping-pong animation frames (no doubled frame at the turn). A B C C B A repeats the middle item for an even count. The last two reverse the list first and mirror around the first item.

和“回文”有什么关系？How does this relate to palindromes?

结果正着读和倒着读完全相同，也就是一个“回文列表”。如果要检查一段文字是不是回文，可以用“回文检测”工具。The result reads the same forwards and backwards, so it's a palindromic list. To check whether a piece of text is a palindrome, use the Palindrome Checker.

分隔符是怎么自动识别的？How is the separator detected automatically?

“自动识别”按以下顺序判断：有换行就按行分隔，否则依次检查 Tab、分号、逗号（含中文逗号和顿号）、竖线，最后才是空格。用逗号、分号或 Tab 分隔时支持 CSV 式的双引号，例如 "北京, 中国" 会被当作一项。需要其他符号时选择“自定义”，可用 \n 和 \t 表示换行和 Tab。输出沿用原来的分隔符（包括自定义分隔符和中文逗号），含分隔符的项会重新加上双引号；空行默认忽略，不算作项目。Auto-detect works in this order: if there are line breaks, each line is an item; otherwise it checks for tabs, semicolons, commas (including the Chinese comma and enumeration comma), pipes and finally spaces. With comma, semicolon or tab separators, CSV-style double quotes are honoured, so "Paris, France" counts as one item. Choose Custom for anything else; \n and \t stand for a new line and a tab. The output keeps the original separator (including a custom one or the Chinese comma), items that contain the separator are quoted again, and blank lines are ignored by default.

处理大段文本会卡吗？Can it handle long text?

「生成对称列表（镜像回文列表）」在浏览器中直接处理，几 MB 以内的文本通常瞬间完成；文本不会离开你的设备。The Create a Symmetric List runs in your browser; text up to a few MB is usually processed instantly and never leaves your device.

「生成对称列表（镜像回文列表）」免费吗？需要注册吗？Is the Create a Symmetric List free? Do I need an account?

「生成对称列表（镜像回文列表）」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Create a Symmetric List is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.