散点图 - 从数据和自定义颜色图中标记绝对大小

Question

我正在尝试实现一个散点图，该散点图可以根据其绝对值自动缩放标记。我不想使用，\pgfplotspointmetatransformed而是使用\pgfplotspointmeta，因为我需要将其与另一个图进行比较，尽管我做不到这一点……

此外，我尝试创建一个颜色图，该颜色图从 z > 0 的颜色范围和 z < 0 的不同颜色范围进行映射。所以你会立即注意到一个值是负数还是正数 - 虽然我有点困惑，所以设置限制的方式是，它在 0 时从红色变为蓝色，因为我已经在使用元数据来表示大小...

\pgfplotstableread{
    A B C
    0    5 -10
    0.5  2   0
    1    7   5  
    1.5 11  20
}\mytable

\begin{tikzpicture}
\pgfplotsset{
    colormap={test}{[2pt]
        rgb255(0pt)=(255, 200, 0);
        rgb255(500pt)=(255, 75, 0);
        rgb255(502pt)=(0, 100, 255);
        rgb255(1000pt)=(0, 255, 255)
    }
}

\begin{axis}[
colorbar 
]

\addplot[
scatter,
only marks,
scatter src=explicit,
mark=*,
scatter/use mapped color={
    draw=mapped color,
    fill=mapped color,
},
scatter/@pre marker code/.append style=
{/tikz/mark size={.6pt+abs(\pgfplotspointmetatransformed/200)}}]
table[meta expr=abs(\thisrow{C})] {\mytable};
\end{axis}
\end{tikzpicture}

我很高兴得到提示，
谢谢

Answer 1

我不太确定我是否理解了你的问题。你的意思是类似下面的内容吗？

% used PGFPlots v1.15
\documentclass[border=5pt]{standalone}
\usepackage{pgfplotstable}
    \pgfplotsset{
        colormap={test}{[2pt]
            rgb255(0pt)=(255, 200, 0);
            rgb255(500pt)=(255, 75, 0);
            rgb255(502pt)=(0, 100, 255);
            rgb255(1000pt)=(0, 255, 255)
        },
    }
\begin{document}
\begin{tikzpicture}
    \begin{axis}[
        colorbar,
        % because you want the color change at zero but don't have "symmetric"
        % data, you have to give the `point meta min' and `point meta max'
        % values manually
        point meta min=-20,
        point meta max=20,
    ]
        \addplot[
            scatter,
            only marks,
            scatter src=explicit,
            mark=*,
            scatter/use mapped color={
                draw=mapped color,
                fill=mapped color,
            },
            % store the (original) of "C" in a macro ...
            visualization depends on={\thisrow{C} \as \perpointmarksize},
            scatter/@pre marker code/.append style={
                % ... and use this macro here
                % (please note that I have changed the values a bit )
                /tikz/mark size={1pt+abs(\perpointmarksize/5)}
            },
        % because of a bug in PGFPlots (<https://sourceforge.net/p/pgfplots/bugs/109/>)
        % you have to give the table explicitly like here or in a file to not get an
        % error message
        % (it is not allowed to give the table as a command)
        ] table [meta=C] {
            A B C
            0    5 -10
            0.5  2   0
            1    7   5
            1.5 11  20
        };
    \end{axis}
\end{tikzpicture}
\end{document}