为什么我的每个标签/样式都没有显示微小节点？

Question

造成这种情况的原因有很多，但最主要的原因是你没有有TikZ 意义上的任何“标签节点”。标签节点是应用于节点本身的节点，如\node [label=above:I am a label node] {I am the main node};。您使用的节点只是“常规”节点。

说你可以想到然后陈述例如every node/.append style={font=\tiny,green}（在\tikzset），但因为一切包含一些文本的节点，这比你想要的要多得多。试一试看看会发生什么。

我允许自己稍微修改一下你的 MWE，并重新排序了一些内容。然后我评论了所有“有点奇怪”/“不直接”的内容，以防你还想了解“微小节点”问题以外的其他内容。

如果您只对“微小节点内容”感兴趣，请搜索被虚线包围的块。

有关更多详细信息，请查看代码中的注释。

\documentclass[border=5pt]{standalone}
\usepackage{pgfplots}
% -----------------------------------------------------------------------------
% one possibility to show tiny labels is to define a new style which you
% apply later to the corresponding nodes
\tikzset{
    Label/.style={
        font=\tiny,
        red,
    },
}
% -----------------------------------------------------------------------------
%\pgfplotsset{
%    % this (whole) style isn't *used* in the following tikzpictures/axis
%    % environments so it isn't needed here
%    standard/.style={%Axis format configuration
%        axis x line=middle,
%        axis y line=middle,
%        enlarge x limits=0.15,
%        enlarge y limits=0.15,
%        every label/.style={font=\tiny},
%        every axis x label/.style={
%            at={(current axis.right of origin)},
%            anchor=north west,
%        },
%        every axis y label/.style={
%            at={(current axis.above origin)},
%            anchor=north east,
%        },
%        every axis plot post/.style={
%            mark options={fill=black},
%        },
%    },
%}
\begin{document}
\begin{tikzpicture}[
%    % in this case this statement is not needed
%    baseline=(current bounding box.center),
]
    \begin{axis}[
        axis lines=middle,
        xtick={-1,0,1},
%        % you don't need this, because the tick labels are identical to the ticks
%        xticklabels={-1, 0, 1},
%        % there are no `extra x ticks` so you don't need this as well
%        extra x tick style={
%            xticklabel style={yshift=0.5ex, anchor=south},
%        },
        xmin=-4,
        xmax=4,
        ytick={\empty},
%        % since you don't state `ytick's you don't to provide corresponding labels ...
%        yticklabels={},
        ymin=-2, ymax=2,
        axis on top,
        enlarge y limits=0.35,
        width=6cm,
        xlabel={$n$},
        ylabel={$x[n]$},
        x label style={anchor=north},
        y label style={anchor=west},
    ]
        \addplot+ [ycomb,black,thick] coordinates {
            (-1,1) (0,2) (1,1)
        };
        \node [anchor=south west] at (axis cs:0,2)  {$2$};
        % ---------------------------------------------------------------------
        % as stated earlier there are plenty of ways to achieve what you want
        % to do, here are some possibilities
        %
        % 1. provide what you need directly to the node
        \node [
            anchor=south east,
            font=\tiny,
            red,
        ] at (axis cs:-1,1) {$1$};
        % 2. apply the created style directly to the node
        \node [
            anchor=south west,
            Label,
        ] at (axis cs:1,1)  {$1$};
    \end{axis}
\end{tikzpicture}

\begin{tikzpicture}[
%    baseline=(current bounding box.center),
]
        \pgfplotsset{
            every tick label/.append style={font=\tiny},
%            % this style is a TikZ style for "labels of nodes" and not nodes that are labels,
%            % that is why you don't see any changing font sizes
%            % said that, it is also not needed here
%            every label/.append style={font=\tiny},
        }
    \begin{axis}[
        axis lines=middle,
        xtick={-3,-2,...,3},
        % as you can see the zero isn't shown, although you stated it here
        % this is because of the key `hide obscured x ticks' which is true by default when
        % `axis lines' are set to `middle' or the alias `center'
        xticklabels={{}, {}, {}, 0, 1, 2, 3},
        % also this is strange. You state the ticks at positions -2 and -1, ...
        extra x ticks={-2,-1},
        % ... but apply the numbers -3 and -2 to them. Is that intended?
        extra x tick labels={$-3$,$-2$,$-1$},
        extra x tick style={
            xticklabel style={yshift=0.5ex,anchor=south}, },
        xmin=-4, xmax=4,
        ytick={\empty},
        yticklabels={},
        ymin=-2, ymax=2,
        axis on top,
        enlarge y limits=0.35,
        width=6cm,
        xlabel={$n$},
        ylabel={$y[n]$},
        x label style={anchor=north},
        y label style={anchor=west},
    ]
        \addplot+ [ycomb,black,thick] plot coordinates
            {(-3,0) (-2,-1) (-1,-2) (0,0) (1,2) (2,1) (3,0)
        };
        % ---------------------------------------------------------------------
        % 3. but you could also scope the nodes and apply the style of the
        %    nodes
        \begin{scope}[
            font=\tiny,
            red,
        ]
            \node [anchor=north] at (axis cs:-2,-1) {$-1$};
            \node [anchor=north] at (axis cs:-1,-2) {$-2$};
        \end{scope}
        % 3. or of course apply the style in the scope
        \begin{scope}[
            Label,
        ]
            \node [anchor=west]  at (axis cs:1,2)   {$2$};
            \node [anchor=west]  at (axis cs:2,1)   {$1$};
        \end{scope}
        % ---------------------------------------------------------------------
    \end{axis}
\end{tikzpicture}
\end{document}

Answer 1