[Tex/LaTex] pgfplots: relative node positioning in axis cs

nodespgfplotspositioning

I have got a file to plot with pgfplots. For convenience I'd like to define a measure in the plot. Unfortunately the relative positioning seems to give weird results. If I define the node coordinates manually everything works fine. According to the pgfplots-manual the sin- and cos-operators use degrees. Could you please tell me where my error is?

\documentclass{standalone}
\usepackage{pgfplots}
\usetikzlibrary{calc}
\usetikzlibrary{positioning}
\usepackage{siunitx}

\pgfplotsset{compat=1.10}

\begin{document}

\pgfplotsset{cellmodel/.style={%
width=0.4\linewidth,
height=0.3\textheight,
axis lines=center,
axis equal image,
domain=0:800,
xmin= 0, xmax= 7,
ymin=-1.5, ymax=6.5,
restrict x to domain=0:7,
ticks=none,
}}

\begin{tikzpicture}
\def\angle{-30}
\begin{axis}[cellmodel]
\addplot[mark=x, mark options={solid}, draw=gray!80!black, dashed, thick] coordinates { 
        (0.0,0.5)
        (2.25,0.5)
        (4.5,4.397114317029974)
        (6.75,4.397114317029974)
};

% necessary nodes
\node (two) at (axis cs:2.25,0.5) {};
\node (thr) at (axis cs:4.5,4.397114317029974) {};

% relative nodes
% \node (mes2l)  at ($(two)+({cos(\angle)},{sin(\angle)})$) {test};     % <- doesn't give the correct coordinates
% \node (mes3l)  at ({$(thr)+({cos(\angle)},{sin(\angle)})$}) {test};
% \node (mes2l)  at ($(two)+(axis cs:{cos(\angle)},{sin(\angle)})$) {test};     % <- doesn't give the correct coordinates
% \node (mes3l)  at ({$(thr)+(axis cs:{cos(\angle)},{sin(\angle)})$}) {test};
\node (mes2l)  at (axis cs:3.116025404,0) {};                   % <- correct coordinates
\node (mes3l)  at (axis cs:5.366025404,3.897114317) {};
\draw[<->]  (mes2l.center) -- (mes3l.center) node [below right, midway]{$l$};
\end{axis}
\end{tikzpicture}

\end{document}

Best Answer

Might be easiest to just move the definition of the mes21 and mes31 nodes outside the axis, then they use the coordinate system of the tikzpicture rather than the axis. (I changed the angle to -30.)

enter image description here

\documentclass[border=5mm]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{calc}
\usetikzlibrary{positioning}
\usepackage{siunitx}

\pgfplotsset{compat=1.10}

\begin{document}

\pgfplotsset{cellmodel/.style={%
width=0.4\linewidth,
height=0.3\textheight,
axis lines=center,
axis equal image,
domain=0:800,
xmin= 0, xmax= 7,
ymin=-1.5, ymax=6.5,
restrict x to domain=0:7,
ticks=none,
}}

\begin{tikzpicture}
\def\angle{-30}
\begin{axis}[cellmodel]
\addplot[mark=x, mark options={solid}, draw=gray!80!black, dashed, thick] coordinates { 
        (0.0,0.5)
        (2.25,0.5)
        (4.5,4.397114317029974)
        (6.75,4.397114317029974)
};

% necessary nodes
\coordinate (two) at (axis cs:2.25,0.5) {};
\coordinate (thr) at (axis cs:4.5,4.397114317029974) {};
\end{axis}

\def\scaling{0.4}
\coordinate (mes2l)  at ($(two)+\scaling*({cos(\angle)},{sin(\angle)})$);
\coordinate (mes3l)  at ($(thr)+\scaling*({cos(\angle)},{sin(\angle)})$);
\draw[<->]  (mes2l) -- (mes3l) node [below right, midway]{$l$};
\end{tikzpicture}

\end{document}

Related Solutions

[Tex/LaTex] pgfplots: Placing node on a specific x-position

Here's one approach based on my answer to Label plots in pgfplots without entering coordinates manually. It finds the intersections between the plot and two vertical lines to position and rotate the node. Using this, you can place an arbitrary node at x=4 by adding the option add node at x={4}{[<node options>]{<node text>}} or add node at x={4}{<node text>} to the \addplot options. I've also added an equivalent style add node at y, which places nodes at a specified vertical coordinate on the plot.

Here's an example for using these styles:

\addplot [
    add node at x={-3}{[myarrow, blue]{}},
    add node at x={3}{[orange, fill=white, opacity=0.75,text opacity=1, sloped]{Sloped}}
    ] {-x^2};

\addplot[
    green,
    add node at y={-30}{[myarrow, green]{}},
    add node at y={-5}{Some text}
] {-x^2+2*x-4};

\documentclass{standalone}
\usepackage{pgfplots}
\usetikzlibrary{shapes.geometric, intersections}
\pgfplotsset{compat=1.7}

\begin{document}
\begin{tikzpicture}

\tikzset{
    myarrow/.style={
        sloped,
        isosceles triangle,
        anchor=apex,
        fill=black,
        inner sep=2pt
    }
}

\makeatletter
\def\parsenode[#1]#2\pgf@nil{%
    \tikzset{label node/.style={#1}}
    \def\nodetext{#2}
}

\tikzset{
    add node at x/.style 2 args={
        name path global=plot line,
        /pgfplots/execute at end plot visualization/.append={
                \begingroup
                \@ifnextchar[{\parsenode}{\parsenode[]}#2\pgf@nil
            \path [name path global = position line #1-1]
                ({axis cs:#1,0}|-{rel axis cs:0,0}) --
                ({axis cs:#1,0}|-{rel axis cs:0,1});
            \path [xshift=1pt, name path global = position line #1-2]
                ({axis cs:#1,0}|-{rel axis cs:0,0}) --
                ({axis cs:#1,0}|-{rel axis cs:0,1});
            \path [
                name intersections={
                    of={plot line and position line #1-1},
                    name=left intersection
                },
                name intersections={
                    of={plot line and position line #1-2},
                    name=right intersection
                },
                label node/.append style={pos=1}
            ] (left intersection-1) -- (right intersection-1)
            node [label node]{\nodetext};
            \endgroup
        }
    },
    add node at y/.style 2 args={
        name path global=plot line,
        /pgfplots/execute at end plot visualization/.append={
                \begingroup
                \@ifnextchar[{\parsenode}{\parsenode[]}#2\pgf@nil
            \path [name path global = position line #1-1]
                ({axis cs:0,#1}-|{rel axis cs:0,0}) --
                ({axis cs:0,#1}-|{rel axis cs:1,1});
            \path [yshift=1pt, name path global = position line #1-2]
                ({axis cs:0,#1}-|{rel axis cs:0,0}) --
                ({axis cs:0,#1}-|{rel axis cs:1,1});
            \path [
                name intersections={
                    of={plot line and position line #1-1},
                    name=left intersection
                },
                name intersections={
                    of={plot line and position line #1-2},
                    name=right intersection
                },
                label node/.append style={pos=1}
            ] (left intersection-1) -- (right intersection-1)
            node [label node] {\nodetext};
            \endgroup
        }
    }
}
\makeatother
\begin{axis}[smooth]
\addplot [
    add node at x={-3}{[myarrow, blue]{}},
    add node at x={3}{[orange, fill=white, opacity=0.75,text opacity=1, sloped]{Sloped}}
    ] {-x^2};

\addplot[
    green,
    add node at y={-30}{[myarrow, green]{}},
    add node at y={-5}{Some text}
] {-x^2+2*x-4};
\end{axis}

\end{tikzpicture} 
\end{document}

[Tex/LaTex] How to define the default vertical distance between nodes

I don't really get the question so I hope this is what you wanted. If you include a full document (such that we copy paste and see the problem on our systems) things are much more easier.

Here, you can change the default setting within a scope but your block style had a node distance which was resetting every time it is issued. I've made it 2mm such that we can see the difference easier.

\documentclass[tikz]{standalone}
\usetikzlibrary{arrows,shapes.geometric,positioning}

\begin{document}
\begin{tikzpicture}[decision/.style={diamond, draw, text width=4.5em, text badly centered, node distance=3.5cm, inner sep=0pt},
                    block/.style   ={rectangle, draw, text width=6em, text centered, rounded corners, minimum height=4em, minimum height=2em},
                    cloud/.style   ={draw, ellipse, minimum height=2em},
                    line/.style    ={draw,-latex'},
                    node distance = 1cm, 
                    auto]
    \node [block] (1st) {1st};
    \node [block, right= of 1st]  (2nd1) {2nd1};
\begin{scope}[node distance=2mm and 10mm]%Here we change it for everything inside this scope
    \node [block, above= of 2nd1] (2nd2) {2nd2};
    \node [block, below= of 2nd1] (2nd3) {2nd3};
    \node [block, right= of 2nd1] (3rd1) {3rd1};
    \node [block, above= of 3rd1] (3rd2) {3rd2};
    \node [block, above= of 3rd2] (3rd3) {3rd3};
\end{scope}
    \node [block, below= of 3rd1] (3rd4) {3rd4};
    \node [block, below= of 3rd4] (3rd5) {3rd5};

    \path [line] (1st) -- (2nd1);
    \path [line] (2nd1) -- (2nd2);
    \path [line] (2nd1) -- (2nd3);
    \path [line] (2nd2) -- (3rd3);
    \path [line] (2nd1) -- (3rd1);
    \path [line] (1st) -- (2nd1);
\end{tikzpicture}
\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] pgfplots: Placing node on a specific x-position

[Tex/LaTex] How to define the default vertical distance between nodes

Related Question