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是否可以选择 ycomb 的基线？

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是否可以选择 ycomb 的基线？

是否可以选择（垂直线）的基线ycomb？

例如，在对数刻度中，默认基线位于y=1(或y=10^0)。但我想将其设为y=0(即负无穷大)。原因是如果所有值都低于，则y=1梳子会向上而不是向下 (这令人困惑)。

伊科姆

梅威瑟：

\documentclass{article}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[ymode=log]
\addplot[ycomb,mark=*] coordinates  {% #points 5
( 0, 100 )
( 1, 10 )
( 2, 1 )
( 3, 0.1 )
( 4, 0.01 )
};
\end{axis}
\end{tikzpicture}
\end{document}

答案1

您可以设置log origin=infty让ycomb情节从情节底部开始：

\documentclass{article}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[ymode=log, log origin=infty]
\addplot[ycomb,mark=*] coordinates  {% #points 5
( 0, 100 )
( 1, 10 )
( 2, 1 )
( 3, 0.1 )
( 4, 0.01 )
};
\end{axis}
\end{tikzpicture}
\end{document}

如果要使梳状图或条形图从轴的顶部开始，则必须重新定义内部宏。将以下代码块放入序言中将使该选项log origin=-infty可用，从而使图从顶部开始：

\makeatletter
\pgfplotsset{
    /pgfplots/log origin x/-infty/.code={\def\pgfplots@log@origin@choice@x{2}},
    /pgfplots/log origin y/-infty/.code={\def\pgfplots@log@origin@choice@y{2}},
    /pgfplots/log origin z/-infty/.code={\def\pgfplots@log@origin@choice@z{2}}
}

\def\pgfplots@prepare@ZERO@coordinates{%
    \ifpgfplots@xislinear
        \ifpgfplots@apply@datatrafo@x
            \pgfplotscoordmath{x}{parsenumber}{0}%
            \pgfplotscoordmath{x}{datascaletrafo}{\pgfmathresult}%
            \global\let\pgfplots@logical@ZERO@x=\pgfmathresult
        \else
            \gdef\pgfplots@logical@ZERO@x{0}%
        \fi
        % this works in standard fixed pt math:
        \pgfplotsmathmax{\pgfplots@logical@ZERO@x}{\pgfplots@xmin}%
        \global\let\pgfplots@logical@ZERO@x=\pgfmathresult
        \pgfplotsmathmin{\pgfplots@logical@ZERO@x}{\pgfplots@xmax}%
        \global\let\pgfplots@logical@ZERO@x=\pgfmathresult
    \else
        \if\pgfplots@log@origin@choice@x0%
            \global\let\pgfplots@logical@ZERO@x=\pgfplots@xmin%
        \else
            \if\pgfplots@log@origin@choice@x2%
                \global\let\pgfplots@logical@ZERO@x=\pgfplots@xmax%
            \else
                \gdef\pgfplots@logical@ZERO@x{0}%
            \fi
        \fi
    \fi
    %
    \ifpgfplots@yislinear
        \ifpgfplots@apply@datatrafo@y
            \pgfplotscoordmath{y}{parsenumber}{0}%
            \pgfplotscoordmath{y}{datascaletrafo}{\pgfmathresult}%
            \global\let\pgfplots@logical@ZERO@y=\pgfmathresult
        \else
            \gdef\pgfplots@logical@ZERO@y{0}%
        \fi
        \pgfplotsmathmax{\pgfplots@logical@ZERO@y}{\pgfplots@ymin}%
        \global\let\pgfplots@logical@ZERO@y=\pgfmathresult
        \pgfplotsmathmin{\pgfplots@logical@ZERO@y}{\pgfplots@ymax}%
        \global\let\pgfplots@logical@ZERO@y=\pgfmathresult
    \else
        \if\pgfplots@log@origin@choice@y0%
            \global\let\pgfplots@logical@ZERO@y=\pgfplots@ymin%
        \else
            \if\pgfplots@log@origin@choice@y2%
                \global\let\pgfplots@logical@ZERO@y=\pgfplots@ymax%
            \else
                \gdef\pgfplots@logical@ZERO@y{0}%
            \fi
        \fi
    \fi
    %
    \ifpgfplots@threedim
        \ifpgfplots@zislinear
            \ifpgfplots@apply@datatrafo@z
                \pgfplotscoordmath{z}{parsenumber}{0}%
                \pgfplotscoordmath{z}{datascaletrafo}{\pgfmathresult}%
                \global\let\pgfplots@logical@ZERO@z=\pgfmathresult
            \else
                \gdef\pgfplots@logical@ZERO@z{0}%
            \fi
            \pgfplotsmathmax{\pgfplots@logical@ZERO@z}{\pgfplots@zmin}%
            \global\let\pgfplots@logical@ZERO@z=\pgfmathresult
            \pgfplotsmathmin{\pgfplots@logical@ZERO@z}{\pgfplots@zmax}%
            \global\let\pgfplots@logical@ZERO@z=\pgfmathresult
        \else
            \if\pgfplots@log@origin@choice@z0%
                \global\let\pgfplots@logical@ZERO@z=\pgfplots@zmin%
            \else
                \if\pgfplots@log@origin@choice@z2%
                    \global\let\pgfplots@logical@ZERO@z=\pgfplots@zmax%
                \else
                    \gdef\pgfplots@logical@ZERO@z{0}%
                \fi
            \fi
        \fi
    \fi
    %
    %
    \ifpgfplots@threedim
        \pgfplotsqpointxyz{\pgfplots@logical@ZERO@x}{\pgfplots@logical@ZERO@y}{\pgfplots@logical@ZERO@z}%
    \else
        \pgfplotsqpointxy{\pgfplots@logical@ZERO@x}{\pgfplots@logical@ZERO@y}%
    \fi
    \xdef\pgfplots@ZERO@x{\the\pgf@x}%
    \xdef\pgfplots@ZERO@y{\the\pgf@y}%
    \xdef\pgfplotspointaxisorigin{\noexpand\global\pgf@x=\pgfplots@ZERO@x\space\noexpand\global\pgf@y=\pgfplots@ZERO@y\space}%
    %
    %
    %--------------------------------------------------
    % \pgfkeyslet{/pgfplots/axis/zero/x}\pgfplots@logical@ZERO@x
    % \pgfkeyslet{/pgfplots/axis/zero/y}\pgfplots@logical@ZERO@y
    % \ifpgfplots@threedim
    %   \pgfkeyslet{/pgfplots/axis/zero/z}\pgfplots@logical@ZERO@z
    % \fi
    %-------------------------------------------------- 
}%
\makeatother

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