Consider the following MWE:
\documentclass{article}
\usepackage{calc} %\widthof
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\usepackage{adjustbox}
\usepackage{tikz}
\usetikzlibrary{pgfplots.groupplots}
\usetikzlibrary{shapes}
\usetikzlibrary{positioning}
\usetikzlibrary{decorations.pathreplacing}
% \usepackage{etoolbox}
\usepackage{xstring}
\usepackage{siunitx}
\begin{document}
\def\firstRowA{0}
\def\lastRowA{5}
\def\firstRowB{45}
\def\lastRowB{80}
\begin{center}
\begin{tikzpicture}
\begin{groupplot}[
group style={
group name=my fancy plots,
group size=2 by 1,
yticklabels at=edge left,
%xticklabels at=edge bottom,
%vertical sep=0pt,
horizontal sep=0pt,
},
%width=8.5cm,
height=6cm,
ymin=-6, ymax=6,
domain=0:80,
]
\pgfmathsetmacro{\xminA}{\firstRowA+0.5} %
\pgfmathsetmacro{\xmaxA}{\lastRowA+0.5} %
\typeout{xminA \xminA, xmaxA \xmaxA}
\nextgroupplot[
xmin=\xminA,xmax=\xmaxA,
xtick={0,5,10},
axis y line=left,
%axis x discontinuity=parallel, % disc. is at start, so avoid for first
axis x line=bottom,
x axis line style=-, % switch off the axis arrow tips,
%width=4.5cm, % don't set width,
x=0.1cm, % set x scale (for width)
]
\addplot {x*0};
\addplot {x*0+1};
\pgfmathsetmacro{\xminB}{\firstRowB+0.5} %
\pgfmathsetmacro{\xmaxB}{\lastRowB+0.5} %
\typeout{xminB \xminB, xmaxB \xmaxB}
\nextgroupplot[
% xmin=45.5,xmax=80.5, % this works fine
xmin=\xminB,xmax=\xmaxB,
axis y line=none,
xtick={60,80},
axis x discontinuity=parallel,
axis x line=bottom,
%width=2.0cm, % don't set width,
x=0.1cm, % set x scale (for width)
]
\addplot {0*x};
\addplot {2+0*x};
\end{groupplot}
\end{tikzpicture}
\end{center}
\end{document}
If you compile it as-is, it will fail with:
! Undefined control sequence.
\pgfplots@loc@TMPa ->\xminB
l.73 ]
... which is weird, because the \typeout just before that:
xminA 0.5, xmaxA 5.5
xminB 45.5, xmaxB 80.5
... confirms that, indeed, the \xminB macro is defined and does have a value?
If numbers are entered directly (that is, xmin=45.5,xmax=80.5,) - then the MWE compiles fine, and results with the expected rendering:
Why does this happen - and how can I use a macro for xmin in this position?
EDIT: just solved the problem - seems that I need to "globalize" the second pair of macros: just add this in the code above:
...
\pgfmathsetmacro{\xminB}{\firstRowB+0.5} %
\pgfmathsetmacro{\xmaxB}{\lastRowB+0.5} %
\typeout{xminB \xminB, xmaxB \xmaxB}
% globalize - with expand!
\xdef\xminB{\xminB} % add redefinition
\xdef\xmaxB{\xmaxB} % add redefinition
\nextgroupplot[
...
... then the MWE compiles fine. But I'm still puzzled - how come I do not have to "globalize" the macro pair for the first \nextgroupplot; and yet I must "globalize" the second one?
