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pgfplots：foreach 循环中的动态路径名

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pgfplots：foreach 循环中的动态路径名

我正在尝试使用 pgfplots 生成几个相交的峰值，并在它们重叠的地方使用虚线/点线路径。不过，我在 foreach 循环中的路径名方面遇到了一些问题。以下是代码：

    \documentclass[tikz]{standalone}
    \usepackage{tikz, pgfplots}

    \usetikzlibrary{positioning, intersections}
    \usepgfplotslibrary{fillbetween}

    \pgfmathdeclarefunction{peak}{1}{%
      \pgfmathparse{abs(#1) > 1 ? 0 : cos((0.5*pi*#1) r)^3}%
    }%
    \begin{document}
    \begin{tikzpicture}
    \begin{axis}[width=400pt, height=250pt]

      % overlapping peaks
      \pgfplotsinvokeforeach{-1,0,1}{
        \addplot [name path global = { line#1 },
        domain=#1-1:#1+1, samples=20, smooth, thick, black]
        {peak(x-#1)};
      }

      \path[draw=white, dotted, ultra thick,
      intersection segments={of=line1 and line0}];

      \path[draw=white, dotted, ultra thick,
      intersection segments={of=line0 and line-1}];

    \end{axis}
    \end{tikzpicture}
    \end{document}

我想将最后两个path调用放在某种循环中。问题是如何获取行名称。line#1 and line#1-1在 pgfplots foreach 中尝试过，但不起作用（显然？我仍然不太清楚数学在 pgf 中哪里有效，哪里无效），line\i and line\i-1在\foreach \i循环中尝试过。也不起作用...

还尝试将减法放在一\pgfmathparse{int(#1-1)}\pgfmathresult对中，但总是抱怨缺少\endcsname。

有什么想法吗？此外，任何关于如何实现我想要的更好方法的建议都非常受欢迎...谢谢！

答案1

\path见下文。这通过在调用之前完全展开参数来实现。请注意，您%在左括号处缺少一个，peak这会移动整个图。

\documentclass[tikz]{standalone}
\usepackage{pgfplots}

\usetikzlibrary{positioning,intersections}
\usepgfplotslibrary{fillbetween}

\pgfmathdeclarefunction{peak}{1}{%
    \pgfmathparse{abs(#1) > 1 ? 0 : cos((0.5*pi*#1) r)^3}%
    }%
\begin{document}
\begin{tikzpicture}
    \begin{axis}[width=400pt, height=250pt]
        % overlapping peaks
        \pgfplotsinvokeforeach{-1,0,1}{%
            \addplot [name path = { line#1 },
            domain=#1-1:#1+1, samples=20, smooth, thick, black]
            {peak(x-#1)};
        }
        \foreach \x in {0,...,1}{%
            \pgfmathparse{int(\x-1)};
            \def\arg{of=line\x\space and line\pgfmathresult}%
            \edef\expath{\noexpand\path[draw=white, dotted, ultra thick,
                intersection segments={\arg}];}
            \expath%
        }
    \end{axis}
\end{tikzpicture}
\end{document}

结果

答案2

A元帖子替代方案。更简单的语法？您决定。我稍微作弊了，只绘制了一条曲线，然后通过简单地左右移动来复制它。MPintersectiontimes手册中解释了它的工作原理。

在此处输入图片描述

prologues := 3;
outputtemplate := "%j%c.eps";

beginfig(1);

vardef f(expr x) = if abs x > 1: 0 else: (cosd(90x))**3 fi enddef;

path xx, yy, line[];

xx = (left--right) scaled 220 shifted 20 down;
yy = (origin--up)  scaled 180 shifted point 0 of xx;

drawarrow xx withcolor .5 white;
drawarrow yy withcolor .5 white;

s = 1/32;
line2 = ((-1,f(-1)) for x=s-1 step s until 1: -- (x,f(x)) endfor) yscaled 150 xscaled 100;
line1 = line2 shifted 100 left;
line3 = line2 shifted 100 right;

numeric t[];
(t1,t2) = line1 intersectiontimes line2;
(t3,t4) = line2 intersectiontimes line3;

drawoptions(withcolor .67 red);
draw subpath( 0,t1)       of line1; 
draw subpath(t2,t3)       of line2;
draw subpath(t4,infinity) of line3;

drawoptions(dashed withdots scaled 0.7);
draw subpath(t1,infinity) of line1;
draw subpath(t3,infinity) of line2;
draw subpath(0,t2)        of line2;
draw subpath(0,t4)        of line3;

drawoptions();

endfig;
end.

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