Tikz 数组访问问题

Question

我无法访问数组元素：

\documentclass{article}
\usepackage{tikz,ifthen}
\usetikzlibrary{calc,patterns}

\def\PatternArray{%
horizontal lines,%
vertical lines,%
north east lines,%
north west lines,%
grid,%
crosshatch,%
dots,%
crosshatch dots,%
fivepointed stars,%
sixpointed stars,%
bricks,%
checkerboard}

\begin{document}

essai

\pgfmathparse{\PatternArray[0]}
\pgfmathresult
\end{document}

Answer 1

这有效

\documentclass{article}
\usepackage{tikz,ifthen}
\usetikzlibrary{calc,patterns}

\newcommand\PatternArray{{%
  "horizontal lines",%
  "vertical lines",%
  "checkerboard"}}

\begin{document}

\pgfmathparse{\PatternArray[0]}
\pgfmathresult

\pgfmathparse{\PatternArray[2]}
\pgfmathresult

\end{document}

项目周围必须有一对额外的括号；非数字项目应该用双引号引起来。

也许你会喜欢这种不同的方法。索引从 1 开始，但你也可以使用负索引从末尾开始计数。输入更容易，因为前导和尾随空格已被删除。

\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn
\NewDocumentCommand{\definearray}{mm}
 {
  \clist_gclear_new:c { g_tarass_array_#1_clist }
  \clist_gset:cn  { g_tarass_array_#1_clist } { #2 }
 }
\NewExpandableDocumentCommand{\getarrayitem}{mm}
 {
  \clist_item:cn { g_tarass_array_#1_clist } { #2 }
 }
\NewExpandableDocumentCommand{\getarraylength}{m}
 {
  \clist_count:c  { g_tarass_array_#1_clist }
 }
\ExplSyntaxOff

\definearray{Pattern}{
  horizontal lines,
  vertical lines,
  north east lines,
  north west lines,
  grid,
  crosshatch,
  dots,
  crosshatch dots,
  fivepointed stars,
  sixpointed stars,
  bricks,
  checkerboard
}

\begin{document}

\getarraylength{Pattern}

\getarrayitem{Pattern}{1}

\getarrayitem{Pattern}{-2}

\end{document}