Scale error bars with y bar

Question

I scaled the y bar is in example:

How to scale existing coordinates data in pgfplots?

the only problem is, that my error bar stays unchanged. Hence it's size is totally wrong.

Hi can I scale the error accordingly to the y bar?

Here my example:

\documentclass{article}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis} [
ymin=0,
symbolic x coords={one,two,three, four},
xtick=data,
ylabel={$y$},
y filter/.code={\pgfmathparse{#1*1000}\pgfmathresult},
]
\addplot[ybar, fill=red!30, error bars/error bar style={red}] 
plot [error bars/.cd, y dir=both, y explicit, error mark options={rotate=90,mark size=4pt}] coordinates
{(one,0.00981)+-(one,0.00002)
    (two,0.00482)+-(two,0.00002)
    (three,0.00478)+-(three,0.00001)
    (four,0.01003)+-(four,0.00003)};
\end{axis} 
\end{tikzpicture}
\end{document}

Solving this is nontrivial because the error bars are drawn with plain TikZ and you will easily run into dimension too large errors if you apply your multiplication by 1000. The much cleaner way IMHO would be to just scale the y coordinates in the input. — , Aug 15 '19 at 01:24

score 1 · Answer 1 · edited Jun 10 '20 at 12:32

With units library you can achieve this by using:

    change y base,
    y SI prefix=milli,

Note that I have increased the error value (10x) so that it will be visible.

LaTeX source

\documentclass[border=3mm]{standalone}
\usepackage{pgfplots}
\usepgfplotslibrary{units}
\begin{document}
\begin{tikzpicture}
\begin{axis} [
title=no scaling,
ymin=0,
symbolic x coords={one,two,three, four},
xtick=data,
ylabel={$y$},
%y filter/.code={\pgfmathparse{#1*1000}\pgfmathresult},
]
\addplot[ybar, fill=red!30, error bars/error bar style={red}] 
plot [error bars/.cd, y dir=both, y explicit, error mark options={rotate=90,mark size=4pt}] coordinates
{(one,0.00981)+-(one,0.0002)
    (two,0.00482)+-(two,0.0002)
    (three,0.00478)+-(three,0.0001)
    (four,0.01003)+-(four,0.0003)};
\end{axis} 
\end{tikzpicture}%
\begin{tikzpicture}
\begin{axis} [
title=after scaling,
ymin=0,
symbolic x coords={one,two,three, four},
xtick=data,
ylabel={$y$},
%y filter/.code={\pgfmathparse{#1*1000}\pgfmathresult},
    change y base,
    y SI prefix=milli,
]
\addplot[ybar, fill=red!30, error bars/error bar style={red}] 
plot [error bars/.cd, y dir=both, y explicit, error mark options={rotate=90,mark size=4pt}] coordinates
{(one,0.00981)+-(one,0.0002)
    (two,0.00482)+-(two,0.0002)
    (three,0.00478)+-(three,0.0001)
    (four,0.01003)+-(four,0.0003)};
\end{axis} 
\end{tikzpicture}
\end{document}

score 1 · Answer 2 · answered Aug 17 '19 at 10:41

I personally don't like stating coordinates to the \addplot command, because this is much harder to write as a table and also doesn't allow easy manipulation of the data. So I converted your coordinates to a table and then applied the scaling of the values to both, i.e. the y values and the y error values.

% used PGFPlots v1.16
\documentclass[border=5pt]{standalone}
\usepackage{pgfplots}
    \pgfplotsset{compat=1.3}
\begin{document}
\begin{tikzpicture}
    \begin{axis}[
        ymin=0,
        symbolic x coords={one,two,three, four},
        xtick=data,
        ylabel={$y$},
    ]
        \addplot[
            ybar,
            fill=red!30,
            error bars/error bar style={red},
            error bars/.cd,
                y dir=both,
                y explicit,
                error mark options={
                    rotate=90,
                    mark size=4pt,
                },
        ] table [
            x=x,
            y expr={1000*\thisrow{y}},
            y error expr={1000*\thisrow{yerr}},
        ] {
                             % scaled by value of 10 so they can be seen
            x       y        yerr
            one     0.00981  0.0002
            two     0.00482  0.0002
            three   0.00478  0.0001
            four    0.01003  0.0003
        };
    \end{axis}
\end{tikzpicture}
\end{document}

score 0 · Answer 3 · answered Aug 15 '19 at 02:58

In my opinion, that figure can be drawn with plain TikZ. We can change scaling as we wish.

\documentclass[tikz,border=5mm]{standalone}
\begin{document}
\begin{tikzpicture}[yscale=.5,xscale=1.7]
\foreach \i/\itext/\ivalue in 
{1/one/9.81,2/two/4.82,3/three/4.78,4/four/10.03}
\draw[blue,line width=4mm] 
(\i,0) node[below,black]{\itext}--+(90:\ivalue); 
\foreach \j in {0,2,...,10}
\draw 
(.5,\j) node[left]{\j}--+(0:1mm)
(4.5,\j)--+(180:1mm);
\draw (.5,0) rectangle (4.5,11);
\path (current bounding box.west) node[left=5mm,rotate=90]{$y$};
\end{tikzpicture}
\end{document}

Scale error bars with y bar

3 Answers3

LaTeX source