Why is the information not rendered?

Question

Here's the code I want to compile:

\documentclass{article}
\usepackage{tikz, pgfplots}
\usepgfplotslibrary{dateplot}
% from https://tex.stackexchange.com/a/288225/231104
\def\pgfplotslibdateplothour:minutetofloat#1:#2.{
    \pgfmathparse{#1+#2/60}
}
\def\pgfplotslibdateplofloattothour:minute#1.{
    \pgfmathsetmacro\hour{int(floor(#1))}
    \pgfmathsetmacro\minute{int((#1-\hour)*60)}
    \ifnum\hour<10\edef\hour{0\hour}\fi
    \ifnum\minute<10\edef\minute{0\minute}\fi
}
\pgfplotsset{
    /pgfplots/time coordinates in/.code={%
        \pgfkeysdef{/pgfplots/#1 coord trafo}{%
            \pgfplotslibdateplothour:minutetofloat##1.
        }
        \pgfkeysdef{/pgfplots/#1 coord inv trafo}{
            \pgfplotslibdateplofloattothour:minute##1.
        }
    }
}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
time coordinates in=x,
xticklabel={\hour:\minute},
]
\addplot coordinates {
(10:00, 0)
(10:30, 25)
(10:40, 28)
(11:00, 40)
(11:15, 42)
(11:30, 50)
};
\end{axis}
\end{tikzpicture}
\end{document}

But on compiling, it just gives a 'Something went wrong' sign. Seems like the code misses something essential, but I couldn't find what.

Please help, thanks!

score 1 · Accepted Answer · answered Apr 29 '21 at 14:51

The PGFPLOTS manual mentions in the chapter on user transformations (page 386 for version 1.17):

Remark: It might be necessary to set \pgfplotsset{ xticklabel={\tick}, scaled x ticks=false, plot coordinates/math parser=false, } in order to avoid number formatting routines on \tick or numerics for tick scale methods.

A bit of experimentation shows that only plot coordinates/math parser=false is necessary in this case. This allows the function defined in the code to transform for example 10:30 to 10.5, which PGFplots can use to find the correct position on the x axis.

Another issue is the inverse transformation, from for example 10.5 back to 10:30. Because there is a . in 10.5 the pattern in the float to hour function, which is floattothour:minute#1., sees only the 10 and then assumes the argument is complete. Changing this to, e.g., : fixes this issue, so floattothour:minute#1:, in the function header but also in the call within coord inv trafo.

MWE:

\documentclass{article}
\usepackage{tikz, pgfplots}
\pgfplotsset{compat=newest}
\usepgfplotslibrary{dateplot}
% from https://tex.stackexchange.com/a/288225/231104
\def\pgfplotslibdateplothour:minutetofloat#1:#2.{
    \pgfmathparse{#1+#2/60}
}
\def\pgfplotslibdateplofloattothour:minute#1:{
    \pgfmathsetmacro\hour{int(floor(#1))}
    \pgfmathsetmacro\minute{int((#1-\hour)*60)}
    \ifnum\hour<10\edef\hour{0\hour}\fi
    \ifnum\minute<10\edef\minute{0\minute}\fi
}
\pgfplotsset{
    /pgfplots/time coordinates in/.code={%
        \pgfkeysdef{/pgfplots/#1 coord trafo}{%
            \pgfplotslibdateplothour:minutetofloat##1.
        }
        \pgfkeysdef{/pgfplots/#1 coord inv trafo}{
            \pgfplotslibdateplofloattothour:minute##1:
        }
    }
}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
plot coordinates/math parser=false,
time coordinates in=x,
xticklabel={\hour:\minute},
]
\addplot coordinates {
(10:00, 0)
(10:30, 25)
(10:40, 28)
(11:00, 40)
(11:15, 42)
(11:30, 50)
};
\end{axis}
\end{tikzpicture}
\end{document}

Result:

Why is the information not rendered?

1 Answers1