Csdrhrt

I have the following diagram and I'd like to annotate and add some arrows but getting a little rotate-confused with the lines and text. I've attached the tikz code I'm working with below and an image with the lines and labels drawn in ..

documentclass[tikz,border=3.14mm]{standalone}

usepackage{pgfplots}

pgfplotsset{compat=1.14}

begin{document}



pgfmathsetmacro{offset}{0.05}

begin{tikzpicture}[font=sffamilysmall,

declare function={gauss(x,y,z)=offset+1.2/(y*sqrt(2*pi))*exp(-((x- z)^2)/(2*y^2));}]



begin{axis}[samples=101,smooth,hide axis,width=20cm,height=8cm]

addplot [domain=-3:3] ({gauss(x,1,0)},x);

addplot [domain=-3:3] ({1+gauss(x,1,0)},x);



draw[-latex] (0,-3) --  (0,3) coordinate[pos=0.35](x1) coordinate[pos=0.5] (y1) node[below right,rotate=-90]{$X_k$};

draw[-latex] (1,-3) -- (1,3) coordinate[pos=0.60](x2) coordinate[pos=0.5](y2) node[below right,rotate=-90]{$X_1$};

addplot[-latex] coordinates{(-0.5,-4) (2,-4)};

path (0,-4) coordinate (z1) (1,-4) coordinate (z2) (2,-4) coordinate (z3);



coordinate (t0) at (-0.45,-4.1);

coordinate (t) at (2,-4.1);

coordinate (xi) at (-0.5,4);

addplot[-latex] coordinates{(-0.5,-4.2) (-0.5,4)}; % yaxis

end{axis}



foreach X in {1,2}

{

draw ([xshift=-1mm]yX) -- ([xshift=1mm]yX);

draw ([yshift=1mm]zX) -- ([yshift=-1mm]zX) node[below] {$t_X$};

}



node[anchor=north east] at (t) {time};

node[anchor=north east] at (xi) {$X$};



end{tikzpicture}

end{document}

You can add the lines inside axis and use these coordinates. I've also added clips=false to avoid problems with tip arrow draw below the axis.

documentclass[tikz,border=4mm]{standalone}

usepackage{pgfplots}

pgfplotsset{compat=1.14}

begin{document}



pgfmathsetmacro{offset}{0.05}

begin{tikzpicture}[font=sffamilysmall,

declare function={gauss(x,y,z)=offset+1.2/(y*sqrt(2*pi))*exp(-((x- z)^2)/(2*y^2));}]



begin{axis}[samples=101,smooth,hide axis,width=20cm,height=8cm, clip=false]

addplot [domain=-3:3] ({gauss(x,1,0)},x);

addplot [domain=-3:3] ({1+gauss(x,1,0)},x);



draw[-latex] (0,-3) --  (0,3) coordinate[pos=0.35](x1) coordinate[pos=0.5] (y1) node[below right,rotate=-90]{$X_k$};

draw[-latex] (1,-3) -- (1,3) coordinate[pos=0.60](x2) coordinate[pos=0.5](y2) node[below right,rotate=-90]{$X_1$};

addplot[-latex] coordinates{(-0.5,-4) (2,-4)};

path (0,-4) coordinate (z1) (1,-4) coordinate (z2) (2,-4) coordinate (z3);



coordinate (t0) at (-0.45,-4.1);

coordinate (t) at (2,-4.1);

coordinate (xi) at (-0.5,4);

addplot[-latex] coordinates{(-0.5,-4.2) (-0.5,4)}; % yaxis



draw[->, red] (-0.5,-5)--(0,-5) node[above,midway]{A};

draw[->,red] (0,-1) node[left]{B}--({1+gauss(-1,1,0)},-1)node[below right]{C};

end{axis}



foreach X in {1,2}

{

draw ([xshift=-1mm]yX) -- ([xshift=1mm]yX);

draw ([yshift=1mm]zX) -- ([yshift=-1mm]zX) node[below] {$t_X$};

}



node[anchor=north east] at (t) {time};

node[anchor=north east] at (xi) {$X$};





end{tikzpicture}

end{document}

You have the parametrizations of the Gaussians, so it is easy to define the points B and C as a function of some input parameter, which I call xp here. And then you already export coordinates out of the axis, you could also do this for the arrow labelled A: just draw it outside of the axis. Then there is no need to switch off clip. (In the present setting, you could switch off clip, as demonstrated by Ignasi, but if you are to add more ingredients to your plot, this might not be the optimal way because often enough it is good to have pgfplots clip away auxiliary stuff.)

documentclass[tikz,border=3.14mm]{standalone}

usepackage{pgfplots}

pgfplotsset{compat=1.14}

begin{document}



pgfmathsetmacro{offset}{0.05}

pgfmathsetmacro{xp}{-1}

begin{tikzpicture}[font=sffamilysmall,

declare function={gauss(x,y,z)=offset+1.2/(y*sqrt(2*pi))*exp(-((x- z)^2)/(2*y^2));}]



begin{axis}[samples=101,smooth,hide axis,width=20cm,height=8cm]

addplot [domain=-3:3] ({gauss(x,1,0)},x);

addplot [domain=-3:3] ({1+gauss(x,1,0)},x);





draw[-latex] (0,-3) --  (0,3) coordinate[pos=0.35](x1) coordinate[pos=0.5] (y1) node[below right,rotate=-90]{$X_k$};

draw[-latex] (1,-3) -- (1,3) coordinate[pos=0.60](x2) coordinate[pos=0.5](y2) node[below right,rotate=-90]{$X_1$};

addplot[-latex] coordinates{(-0.5,-4) (2,-4)};

path (0,-4) coordinate (z1) (1,-4) coordinate (z2) (2,-4) coordinate (z3)

(-0.5,-5) coordinate (h1) (0,-5) coordinate (h2);



coordinate (t0) at (-0.45,-4.1);

coordinate (t) at (2,-4.1);

coordinate (xi) at (-0.5,4);

addplot[-latex] coordinates{(-0.5,-4.2) (-0.5,4)}; % yaxis

coordinate (start) at (0,xp);

coordinate (end) at ({1+gauss(xp,1,0)},xp);

end{axis}



foreach X in {1,2}

{

draw ([xshift=-1mm]yX) -- ([xshift=1mm]yX);

draw ([yshift=1mm]zX) -- ([yshift=-1mm]zX) node[below] {$t_X$};

}



draw[red,-latex] (start) node[left]{B} 

-- (end) node[below right]{C};

draw[red,-latex] (h1) -- (h2) node[midway,above]{A};



node[anchor=north east] at (t) {time};

node[anchor=north east] at (xi) {$X$};



end{tikzpicture}

end{document}