TikZ 中的下三角图

Question

我如何在 LaTeX 中输入以下图表（也许 Ti钾Z)？：我想要 10 个要点，按 5 乘 5 矩阵下三角部分的点排列。然后我想要从每个节点指向其正上方节点的箭头。提前致谢！

Answer 1

像这样？

\documentclass[tikz, border=1cm]{standalone}
\newlength\radius
\setlength\radius{2pt}
\begin{document}
\begin{tikzpicture}
    \foreach \i in {0,...,4}{ % rows
        \foreach \j in {0,...,4}{ % columns
            \ifnum\numexpr\j-\i<0\relax % check for lower triangle
                \def\fill{fill}
            \else
                \def\fill{}
            \fi
            \draw[\fill] (\j, -\i) circle (\radius);
            \ifnum\i>0\relax % if not in first row, draw arrow
                \draw[->, blue, shorten <=\radius, shorten >=\radius] (\j, -\i) -- +(0,1);
            \fi
        }
    }
\end{tikzpicture}
\end{document}

删除白点后的代码。

\documentclass[tikz, border=1cm]{standalone}
\newlength\radius
\setlength\radius{2pt}
\begin{document}
\begin{tikzpicture}
    \foreach \i in {0,...,4}{ % rows
        \foreach \j in {0,...,4}{ % columns
            \ifnum\numexpr\j-\i<0\relax % check for lower triangle
                \filldraw (\j, -\i) circle (\radius);
                \ifnum\i>0\relax % if not in first row, draw arrow
                    \draw[->, blue, shorten <=\radius, shorten >=\radius] (\j, -\i) -- +(0,1);
                \fi
            \fi
        }
    }
\end{tikzpicture}
\end{document}

Answer 2

Οὖτις 的漂亮答案的一个变体，使用nodes 而不是circles 来简化绘制箭头：

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
    \foreach \i [evaluate=\i as \u using int(\i-1)] in {0,...,3}{ 
        \foreach \j [evaluate=\j as \v using int(\j-\i)] in {\i,...,3}{ 
            \node[circle, fill, inner sep=2pt] at (\v, \i) (n-\v-\i) {};
            \ifnum\i>0\relax 
                \draw[->, blue] (n-\v-\u) -- (n-\v-\i);
            \fi
        }
    }
\end{tikzpicture}
\end{document}