除了默认值之外，如何对节点的锚点位置进行更多的控制？

Question

tikz 节点有锚点south，north等等，还有south west等等south east......

但是在下图中，我想从一个节点画一条线，该线不是从 开始，而是从和south west中间开始。即从西南角向右移动更多，以便看起来更好。south westsouth

通常，如何创建一个新的锚点位置来绘制除建筑物之外的线条？

举个例子就清楚了。这个 MWE

\documentclass{article}    
\usepackage{tikz}
\usetikzlibrary{shapes,arrows}
\usetikzlibrary{positioning}
\begin{document}
\pagestyle{empty}
    
\tikzstyle{block} = [rectangle, draw, fill=blue!20, 
    text width=5em, text centered, rounded corners, minimum height=4em]
\tikzstyle{line} = [draw, -latex']
    
\begin{tikzpicture}
    % Place nodes
    \node [block] (init) {differential equation};
    %
    \node [block, below right=1cm and -1.5cm  of init] (secondOrder) {second order};
    %
       \node [block, below=1cm of secondOrder] (linearSecondOrder) {linear};
       \node [block, right=1cm of linearSecondOrder] (nonlinearSecondOrder) {non-linear};
    %
    \node [block, below left=1cm and 1cm  of init] (firstOrder) {first order};
    %
       \node [block, below=1cm of firstOrder] (firstOrderDegree1) {degree 1};
           %
           \node [block, below right=.5cm and -1.2cm of firstOrderDegree1] (linearFirstOrder) {linear};
           \node [block, below=.5cm of linearFirstOrder]  (separable) {separable};
           \node [block, below=.5cm of separable]   (bernoulli) {Bernoulli};
       %
       \node [block, left=1cm of firstOrderDegree1] (firstOrderDegreeHigher) {higher degree};
    %
    \node [block,   below right=1cm and 4.5cm of init] (higherOrder) {higher order};
     

    \path [line] (init) -- (firstOrder);
    \path [line] (init) -- (secondOrder);
    \path [line] (init) -- (higherOrder);
    %
    \path [line] (secondOrder) -- (linearSecondOrder);
    \path [line] (secondOrder) -- (nonlinearSecondOrder);
    %
    \path [line] (firstOrder) -- (firstOrderDegree1);
    \path [line] (firstOrder) -- (firstOrderDegreeHigher);
    %
    \path [line] (firstOrderDegree1.south west) -- (linearFirstOrder.west);
    \path [line] (firstOrderDegree1.south west) -- (separable.west);
    \path [line] (firstOrderDegree1.south west) -- (bernoulli.west);    
\end{tikzpicture}    
\end{document}

生成此

实际上我想做的是以下几点，但我认为这比较难，所以我首先尝试看看是否可以先改变锚点位置：

上面的方法更好，但我不知道该怎么做，因为我不知道从哪里开始/到哪里画线。所以如果可能的话，我现在会选择第一个选择。

Answer 1

这是一个使用 的选项forest。

\documentclass{article}

\usepackage[edges]{forest}

\begin{document}

\begin{forest}
for tree={
    draw, rounded corners, fill=blue!20,
    minimum height=1.5cm, minimum width=2cm,
    align=center, base=b,
    s sep=1cm, l sep=.5cm,
    if level<=2{edge=-latex}{edge=red},
}
[differential\\equation
    [first order, calign=last
        [higher\\degree][degree 1, for tree={grow'=0, folder}, s sep=.5cm, before computing xy={l-=.845cm}
            [linear][separable][Bernoulli]
        ]
    ]
    [second order, calign=first
        [linear][nonlinear]
    ]
    [higher order, fit=band]
]
\end{forest}

\end{document}