# Apply shift to (current axis.left of origin)

I was trying to improve the solution at Drawing lines in a plot and give them a label? by using Jake's answer at How to access \xmin, \xmax, \ymin, \ymax from within PGFplots axis environment. So, Jake's answer produces the brown dotted line (the x-axis) with

(current axis.left of origin) -- (current axis.right of origin)


I thought a simple use of tikz's calc library would allow me to adjust the vertical position of the horizontal line. If I want a horizontal line at y=12, for example, I simply use

($(current axis.left of origin)+(axis cs: 0,12)$) -- ($(current axis.right of origin)+(axis cs: 0,12)$)


where I have applied a + (axis cs: 0,12) and same for the other coordinate.

Well, that is great in theory, but doesn't work. Instead, it produces the dashed line in red (which is only half the desired line): ## Notes:

• Instead of doing coordinate calculations, I also tried applying shift={(axis cs: 0,12)} option but that had no effect on the output.

## Code:

\documentclass{article}
\usepackage{pgfplots}
\usetikzlibrary{calc}

\begin{document}
\begin{tikzpicture}
\begin{axis}
\addplot {x*x};

\draw [ultra thick, dotted, draw=brown]
(current axis.left of origin) --
(current axis.right of origin);

\draw [ultra thick, dashed, draw=red]
($(current axis.left of origin) +(axis cs: 0,12)$) --
($(current axis.right of origin)+(axis cs: 0,12)$);
\end{axis}
\end{tikzpicture}
\end{document}

• I think you have to use axis direction cs in this case – Jake Mar 21 '14 at 16:10
• @Jake: Yep that works. Please post that as an answer. Some info re: axis cs and axis direction cs would be useful as well. – Peter Grill Mar 21 '14 at 19:05

## 1 Answer

I really don't know why but this works for me

\documentclass{article}
\usepackage{pgfplots}
\usetikzlibrary{calc}

\pgfplotsset{compat=1.10}

\begin{document}
\begin{tikzpicture}
\begin{axis}
\addplot {x*x};

\draw [ultra thick, dotted, draw=brown]
(current axis.left of origin) --
(current axis.right of origin);

\draw [ultra thick, draw=red]
($(current axis.left of origin)-(axis cs:0,-12)$) --
($(current axis.right of origin)+(axis cs:0,12)$);
\end{axis}
\end{tikzpicture}
\end{document} • Indeed. Very bizarre that a +(0,12) produces incorrect results, yet -(0,-12) produces the desired result. Perhaps a bug then? – Peter Grill Mar 21 '14 at 16:15