x-axis labels different from data in pgfplots

Question

In the following code, I want the labels of the x-axis to be 128,256,1024,2048,4096. However, when I compile it I get 128,256,1020,2050,4100. What am I missing?

\documentclass{article}
\usepackage{pgfplots}
\usepackage{amsmath}
\pgfplotsset{compat=1.14}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
    xlabel={x},
    ylabel={y},
    width=260pt,
    x tick label style={major tick length=0pt},
    xmode=log,
    log ticks with fixed point,
    xtick=data,
    ytick={9,10,11,12,13,14,15,16,17,18,19,20},
    minor y tick num=1,
    ymajorgrids,
    legend style={at={(0.5,0.97)},
    legend entries={{$\epsilon=\tfrac{1}{17}$,},{$\epsilon=\tfrac{1}{16}$,},{$\epsilon=\tfrac{1}{15}$,},$\epsilon=\tfrac{1}{14}$},
    anchor=north,legend columns=-1},
    ybar,
    bar width=5pt,
  ]
  \addplot[fill=red!80,
     error bars/.cd, 
     y dir=plus, 
     y explicit,
    ]
   plot coordinates { 
       (128,9.217) += (0,4.783)
       (256,10.128) += (0,4.872)
       (512,11.125) += (0,5.875)
       (1024,11.918) += (0,5.082)
       (2048,12.785) += (0,5.215)
       (4096,13.994) += (0,5.006)
   };
 \end{axis}
 \end{tikzpicture}
 \end{document}

welcome to tex.se! please extend your code snippet to complete, but small, document (beginning with \documentclas{...} and ending with `\end{document}. help us to help you. — Zarko, Feb 12 '18 at 23:05
To make @Zarko happy, please add begin{tikzpicture} before\begin{axis}. — , Feb 12 '18 at 23:41
Perhaps this is related. At least I interpret it as: if you want xmode=log, you may need to set your labels manually. — , Feb 13 '18 at 00:34
@marmot Adding xtick={128,256,512,1024,2048,4096} doesn't help. — pgfuseranonymous, Feb 13 '18 at 00:43
Yes, I confirm this. It's really odd. Perhaps only @Christian-Feuersänger can solve this. — , Feb 13 '18 at 01:31

score 2 · Answer 1 · answered Feb 13 '18 at 06:55

Without checking the definition of log ticks with fixed point I guess the shown result is because of some rounding of the numbers. So just define your own style and choose the rounding you need.

For details please have a look at the comments in the code.

% used PGFPlots v1.15
\documentclass[border=5pt]{standalone}
\usepackage{amsmath}
\usepackage{pgfplots}
    \pgfplotsset{
        compat=1.14,
        % define your own x tick label style
        % (adapted from <https://tex.stackexchange.com/a/139084/95441>)
        log x ticks with fixed point/.style={
            xticklabel={
                \pgfkeys{/pgf/fpu=true}
                \pgfmathparse{exp(\tick)}%
                \pgfmathprintnumber[fixed,precision=0]{\pgfmathresult}
                \pgfkeys{/pgf/fpu=false}
            },
        },
    }
\begin{document}
\begin{tikzpicture}
    \begin{axis}[
        xlabel={$x$},
        ylabel={$y$},
        width=260pt,
        xmode=log,
        % replace the "default" style ...
%        log ticks with fixed point,
        % ... with the custom style
        log x ticks with fixed point,
        xtick=data,
        x tick label style={
            major tick length=0pt,
        },
        ytick={9,...,20},
        minor y tick num=1,
        ymajorgrids,
        legend style={
            at={(0.5,0.97)},
            anchor=north,
            legend columns=-1,
        },
        legend entries={
            {$\epsilon=\tfrac{1}{17}$,},
            {$\epsilon=\tfrac{1}{16}$,},
            {$\epsilon=\tfrac{1}{15}$,},
            $\epsilon=\tfrac{1}{14}$%
        },
        ybar,
        bar width=5pt,
    ]
        \addplot[
            fill=red!80,
            error bars/.cd,
                y dir=plus,
                y explicit,
        ]  coordinates {
           (128,9.217)   += (0,4.783)
           (256,10.128)  += (0,4.872)
           (512,11.125)  += (0,5.875)
           (1024,11.918) += (0,5.082)
           (2048,12.785) += (0,5.215)
           (4096,13.994) += (0,5.006)
        };
     \end{axis}
 \end{tikzpicture}
 \end{document}

score 1 · Accepted Answer · answered Feb 13 '18 at 06:58

1

Quick and dirty, I know, but for the moment you might use xticklabels={128,256,512,1024,2048,4096} (or xticklabels={128,256,512,{1,024},{2,048},{4,096}}, if you prefer the thousands separator).

answered Feb 13 '18 at 06:58

exilsteira

56

x-axis labels different from data in pgfplots

2 Answers2