foreach 中 local bounding box 命名的 pic 和 node 无法被 fit

根据tex stack exchange 上的回答[tex sc](https://tex.stackexchange.com/questions/533786/failed-to-use-the-local-bounding-box-produced-by-foreach-and-pic)，需要用到`/.expanded`将`\i`完全展开 ```tex \documentclass[tikz]{standalone} \usetikzlibrary{fit} \tikzset{% pics/abc/.style={% code={ \node {this is some path}; } } } \begin{document} \begin{tikzpicture} %fit失败 \foreach \i in {1,...,3} \pic[local bounding box/.expanded=a\i] at (0,\i) {abc}; \node[draw,fit={(a1)(a2)(a3)}] {}; %fit成功 \pic[local bounding box=a4] at (10,4) {abc}; \pic[local bounding box=a5] at (10,5) {abc}; \pic[local bounding box=a6] at (10,6) {abc}; \node[draw,fit={(a4)(a5)(a6)}] {}; \end{tikzpicture} \end{document} ```

一个“治标”的解决方法是，在循环里面用`node`把`pic`套起来，就可以在外部通过`fit` `node`名称，从而间接`fit` `pic`了。缺点是，会多了默认的`inner sep=.333em`，需要人为取消。 ```tex \documentclass[tikz]{standalone} \usetikzlibrary{fit} \tikzset{ pics/abc/.style={ code={ \node {this is some path}; } } } \begin{document} \begin{tikzpicture} \foreach \i in {1,...,3} { \pic[local bounding box=a\i] at (0,\i) {abc}; \node[fit=(a\i),local bounding box=Az\i] (A\i) {}; } \node[draw,fit={(A1)(A2)(A3)}] {}; \pic[local bounding box=a4] at (4,1) {abc}; \pic[local bounding box=a5] at (4,2) {abc}; \pic[local bounding box=a6] at (4,3) {abc}; \node[draw,fit={(a4)(a5)(a6)}] {}; \foreach \i in {1,...,3} { \pic[local bounding box=b\i] at (8,\i) {abc}; \node[fit=(b\i),inner sep=0pt] (B\i) {}; } \node[draw,fit={(B1)(B2)(B3)}] {}; \end{tikzpicture} \end{document} ```  另外，若`foreach`中的`node`也用`local bounding box`命名，同样无法被`fit`，即 ```tex %fit失败 \foreach \i in {1,...,3} \node[local bounding box=a\i] at (0,\i) {}; \node[draw,fit={(a1)(a2)(a3)}] {}; %fit成功 \foreach \i in {1,...,3} \node (a\i) at (0,\i) {}; \node[draw,fit={(a1)(a2)(a3)}] {}; ```

```tex \tikzset{ seagull/.pic={ \draw (-3mm,0) to [bend left] (0,0) to [bend left] (3mm,0); } } \tikz{ \foreach \i in {1,2,3}{ \pic [local bounding box={a\i},] at(0,\i) {seagull}; } } \ifcsname pgf@sh@ns@a1\endcsname yes \else no \fi \csname pgf@sh@np@a1\endcsname \meaning\southwest ``` 看一下这段代码的执行结果就知道为什么会 fit 失败了。原因跟 **pgfplotstable** 手册(1.16版)的最后一页的例子一样。 从你的代码看，你可能需要 `current path bounding box` 这个预定义 node.