Show x-labels as time every two hours with pgfplots{dateplot}

Question

I'm trying to plot a simple graph from .csv. I'm using the answer of https://tex.stackexchange.com/a/83929/164280 as basis. I get a could not parse input '00:00:00' as floating point error. I do want to plot the data as time series. How do I work around this?

MWE:

\documentclass[11pt, twoside, a4paper]{report}
\usepackage{pgfplots}
\begin{document}
    \begin{figure}
        \begin{tikzpicture}
        \begin{axis}
        \addplot table [x=Time, y=AC, col sep=semicolon] {mayriso.csv};
        \end{axis}
        \end{tikzpicture}
    \end{figure}
\end{document}

Datafile snippet:

Time;AC
00:00:00;-0.4442
00:01:00;-0.4445

Edit:

Thanks to marmot, this is now my new MWE:

\documentclass[11pt, twoside, a4paper]{report}
\usepackage[inner = 25mm, outer = 25mm,  top = 30mm, bottom = 20mm, headheight = 13.6pt]{geometry}
\usepackage{pgfplots}
\usepgfplotslibrary{dateplot}
\pgfplotsset{
    compat=1.16,
    }


\begin{document}

\begin{figure}[h]
    \centering
    \begin{tikzpicture}
    \begin{axis}[width = 0.7\textwidth, height = 0.4\textwidth, date coordinates in=x, xticklabel={\hour.\minute},
    ymin=0, ylabel={AC output power (kW)}, axis lines*=left,ymajorgrids,]
    \addplot [ultra thick, smooth, green!50!black,] table [x=Time, y=AC, col sep=semicolon] {riso.csv};
    \end{axis}
    \end{tikzpicture}
    \caption{caption}
    \label{fig:other version}
\end{figure}

\end{document}

The issue is that the x labels are ugly. I want the x-labels to show hours at regular intervals, so 00:00, 02:00, 04:00 or something like that. I also want the graph x label to start at 00:00 and end at 24:00. How do I do this?

Answer 1

Well, it complains that it is not a floating number because it is none. One workaround is to use dateplot, prepend year, month and day and then do the plot.

\documentclass[11pt, twoside, a4paper]{report}
\usepackage{filecontents}
\begin{filecontents*}{mayriso.csv}
Time;AC
2018-08-08 00:00;-0.4442
2018-08-08 00:01;-0.4445
\end{filecontents*}
\usepackage{pgfplots}
\usepgfplotslibrary{dateplot}
\begin{document}
    \begin{figure}
        \begin{tikzpicture}
        \begin{axis}[date coordinates in=x,
        xticklabel={\hour.\minute}]
        \addplot table [x=Time, y=AC, col sep=semicolon] {mayriso.csv};
        \end{axis}
        \end{tikzpicture}
    \end{figure}
\end{document}

Or you need to find a way that your data gets interpreted. Perhaps the dateplot library could be a good starting point to write such a parser. Or you work with symbolic coordinates, but then of course the values won't determine the x coordinates.

---

If someone sees that, here is where I am stuck. I tried many things, but could not convince pgfplots to parse the times coordinates.

\documentclass[11pt, twoside, a4paper]{report}
\usepackage{pgfplots}
\usepgfplotslibrary{dateplot}
\pgfplotsset{compat=1.16}
\usepackage{filecontents}
\begin{filecontents*}{mayriso.csv}
Time;AC
00:00:00;-0.4442
00:01:00;-0.4445
\end{filecontents*}
\makeatletter 
\def\myparse#1:#2:#3 #4{%
        \pgf@xa=#1pt
        \pgf@xb=#2pt
        \divide\pgf@xb by60
        \advance\pgf@xa by\pgf@xb
        \pgf@xb=#3pt
        \divide\pgf@xb by3600
        \advance\pgf@xa by\pgf@xb
        \ifdim\pgf@xa<0pt
                \pgf@xa=0pt
        \fi
        \edef#4{\pgf@sys@tonumber\pgf@xa}%
}% 
\newcommand\TimeParse[1]{\myparse#1 \tmp%
\tmp
}
\makeatother

\begin{document}
\TimeParse{00:01:00}
        \begin{tikzpicture}
        \begin{axis}
        %\addplot table [x expr=\TimeParse{\thisrow{Time}}, y=AC, col sep=semicolon] {mayriso.csv};
        \end{axis}
        \end{tikzpicture}
 \end{document}

It does parse the time, just not in the plot.