我想畫一個像這樣的多層感知器：
我創建了以下程式碼：
\documentclass[tikz, margin=3mm] {standalone}
\usetikzlibrary{arrows.meta, matrix}
\begin{document}
\begin{tikzpicture}[
> = Stealth, thick,
plain/.style = {draw=none, fill=none, yshift=11mm, text width=7ex, align=center},% for text in images,
ec/.style = {draw=none, fill=none},% for emty cells,
net/.style = {matrix of nodes, % for matrix style
nodes={circle,fill=blue!20, draw, semithick, minimum width=12mm, inner sep=0mm},% circles in image
nodes in empty cells,% for not used cells in matrix
column sep = 16mm, % distance between columns in matrix
row sep = -3mm % distance between rows in matrix
}]
\matrix[net] (m)% m is matrix name, it is used for names of cell: firs has name m-1-1
% in empty space between ampersands will show circles:
% i.e.: nodes of the neural network
{
|[plain]| Input layer & |[plain]| Hidden layer & |[plain]| Output layer \\
|[ec]| & |[ec]| & |[ec]| \\
& -1 & |[ec]| \\
|[ec]| & |[ec]| & |[ec]| \\
|[ec]| & |[ec]| & 3 \\
|[ec]| & |[ec]| & |[ec]| \\
& -1 & |[ec]| \\
|[ec]| & |[ec]| & |[ec]| \\
};
\draw[<-] (m-3-1) -- node[left, xshift=-0.65cm] {$x_1$} +(-2cm,0);
\draw[<-] (m-7-1) -- node[left, xshift=-0.65cm] {$x_2$} +(-2cm,0);
\draw[->] (m-5-3) -- node[right, xshift=0.65cm] {$y$} +(2cm,0);
\draw[->] (m-3-1) -- node[above] {$-2$} (m-3-2);
\draw[->] (m-3-1) -- node[below, yshift=-0.75cm, xshift=-0.5cm] {$2$} (m-7-2);
\draw[->] (m-7-1) -- node[above, yshift=0.75cm, xshift=-0.5cm] {$2$} (m-3-2);
\draw[->] (m-7-1) -- node[below] {$-2$} (m-7-2);
\draw[->] (m-3-2) -- node[above] {$2$} (m-5-3);
\draw[->] (m-7-2) -- node[below] {$2$} (m-5-3);
\end{tikzpicture}
\end{document}
這是上面的輸出：
問題是，每當我刪除第一層中的節點時，tikz 繪圖都是不對稱的。當我在其中畫一個“1”時，圖片是對稱的。
那我該如何解決這個問題呢？我嘗試調整最小尺寸，但這沒有幫助。
謝謝你！
答案1
如果將內部節點錨點保持為（圖表將再次對稱），則Amatrix of nodes將內部節點錨點變更為。basecenternodes={... anchor=center}
\documentclass[tikz, margin=3mm] {standalone}
\usetikzlibrary{arrows.meta, matrix}
\begin{document}
\begin{tikzpicture}[
> = Stealth, thick,
plain/.style = {draw=none, fill=none, yshift=11mm, text width=7ex, align=center},% for text in images,
ec/.style = {draw=none, fill=none},% for emty cells,
net/.style = {matrix of nodes, % for matrix style
nodes={circle,fill=blue!20, draw, semithick, minimum width=12mm, inner sep=0mm, anchor=center},% circles in image
nodes in empty cells,% for not used cells in matrix
column sep = 16mm, % distance between columns in matrix
row sep = -3mm % distance between rows in matrix
}]
\matrix[net] (m)% m is matrix name, it is used for names of cell: firs has name m-1-1
% in empty space between ampersands will show circles:
% i.e.: nodes of the neural network
{
|[plain]| Input layer & |[plain]| Hidden layer & |[plain]| Output layer \\
|[ec]| & |[ec]| & |[ec]| \\
& -1 & |[ec]| \\
|[ec]| & |[ec]| & |[ec]| \\
|[ec]| & |[ec]| & 3 \\
|[ec]| & |[ec]| & |[ec]| \\
& -1 & |[ec]| \\
|[ec]| & |[ec]| & |[ec]| \\
};
\draw[<-] (m-3-1) -- node[left, xshift=-0.65cm] {$x_1$} +(-2cm,0);
\draw[<-] (m-7-1) -- node[left, xshift=-0.65cm] {$x_2$} +(-2cm,0);
\draw[->] (m-5-3) -- node[right, xshift=0.65cm] {$y$} +(2cm,0);
\draw[->] (m-3-1) -- node[above] {$-2$} (m-3-2);
\draw[->] (m-3-1) -- node[below, yshift=-0.75cm, xshift=-0.5cm] {$2$} (m-7-2);
\draw[->] (m-7-1) -- node[above, yshift=0.75cm, xshift=-0.5cm] {$2$} (m-3-2);
\draw[->] (m-7-1) -- node[below] {$-2$} (m-7-2);
\draw[->] (m-3-2) -- node[above] {$2$} (m-5-3);
\draw[->] (m-7-2) -- node[below] {$2$} (m-5-3);
\end{tikzpicture}
\end{document}
