pgfplots with symbolic x coords and error bars

Question

I am trying to plot explicit error bars like this:

\begin{tikzpicture} 
\begin{axis} [symbolic x coords={Lighting,Computers,Total}]
\addplot+[only marks] plot[error bars/.cd, y dir=both, y explicit]
coordinates{
    (Lighting,0.12) +- (0.31,0.03)
    (Computers,0.06) +- (0.12,0.01) 
    (Total,0.07) +- (0.14,0.02)
};
\end{axis} 
\end{tikzpicture}

Except this produces a constant error instead of the explicit values I have provided. For example, for Lighting, it produces 0.12 +-0.03 (see below). Did I misread the manual?! There is also some weirdness with the labels on the x-axis and I'd rather not have the y-axis use exponential notation for y<0.1. (I tried posting the output, but apparently I need more cred!)

Answer 1

Starting from PGFPlots version 1.9, asymmetric error bars are directly supported:

\documentclass{article} 
\usepackage{pgfplots}

\pgfplotstableread{
x         y    y-max  y-min
Lighting  0.12 0.31   0.03
Computers 0.06 0.12   0.01 
Total     0.07 0.14   0.02
}{\mytable}

\begin{document}    
\begin{tikzpicture}
\begin{axis} [
    ymin=0,
    symbolic x coords={Lighting,Computers,Total},
    xtick=data
]
\addplot [only marks] 
  plot [error bars/.cd, y dir=both, y explicit]
  table [y error plus=y-max, y error minus=y-min] {\mytable};
\end{axis} 
\end{tikzpicture}

\end{document}

Answer 2

Update

From version 1.12.1 of pgfplots (at least), asymmetric error values are supported through y error plus, and y error minus:

\documentclass{article} 
\usepackage{pgfplots}
\usepackage{pgfplotstable}

\pgfplotstableread{
x         y    y-max  y-min
Lighting  0.12 0.31   0.03
Computers 0.06 0.12   0.01 
Total     0.07 0.14   0.02
}{\mytable}

\begin{document}

\begin{tikzpicture}[scale=1.3] 
\begin{axis} [symbolic x coords={Lighting,Computers,Total},xtick=data]
\addplot+[forget plot,only marks] 
  plot[error bars/.cd, y dir=both, y explicit]
  table[x=x,y=y,y error plus expr=\thisrow{y-max},y error minus expr=\thisrow{y-min}] {\mytable};
\end{axis} 
\end{tikzpicture}

\end{document}

Old versions of pgfplots

I read the documentation for pgfplots but, as far as I could see, asymmetric error bars are not supported (error bars will use one same value); a possible workaround is to use two addplots: one for the upper error values, and the other one for the lower error values; in the following example I used \pgfplotstableread from the pgfplotstable package to store the data and easily reuse it. Here's a little example:

\documentclass{article} 
\usepackage{pgfplots}
\usepackage{pgfplotstable}

\pgfplotstableread{
x         y    y-max  y-min
Lighting  0.12 0.31   0.03
Computers 0.06 0.12   0.01 
Total     0.07 0.14   0.02
}{\mytable}

\begin{document}

\begin{tikzpicture}[scale=1.3] 
\begin{axis} [symbolic x coords={Lighting,Computers,Total},xtick=data]
\addplot+[forget plot,only marks] 
  plot[error bars/.cd, y dir=plus, y explicit]
  table[x=x,y=y,y error expr=\thisrow{y-max}] {\mytable};
\addplot+[only marks,xticklabels=\empty] 
  plot[error bars/.cd, y dir=minus, y explicit]
  table[x=x,y=y,y error expr=\thisrow{y-min}] {\mytable};
\end{axis} 
\end{tikzpicture}

\end{document}

Answer 3

Below is my try at guessing what your problem is. From the comments, it is always a good practice to include a fully-compilable MWE.

\documentclass[10pt]{article}

\usepackage{pgfplots}
\pgfplotsset{compat=1.5.1}

\begin{document}
\begin{tikzpicture}
\begin{axis} [%log ticks with fixed point
,symbolic x coords={Lighting,Computers,Total}]
\addplot+[only marks] plot[error bars/.cd, y dir=both, y explicit]
coordinates{
    (Lighting,0.12) +- (0.31,0.03)
    (Computers,0.06) +- (0.12,0.01) 
    (Total,0.07) +- (0.14,0.02)
};
\end{axis} 
\end{tikzpicture}

\end{document}

Here is the output. (Though I still encourage to post your picture so that we can see what's really happening in your actual case.)

Note the repeated labels.

To resolve this, I manually set the width smaller. (I think the default is 7 cm.) Here, I used width=6.5cm.

\begin{tikzpicture}
\begin{axis} [%log ticks with fixed point
,symbolic x coords={Lighting,Computers,Total},width=6.5cm]% Set the width smaller
\addplot+[only marks] plot[error bars/.cd, y dir=both, y explicit]
coordinates{
    (Lighting,0.12) +- (0.31,0.03)
    (Computers,0.06) +- (0.12,0.01) 
    (Total,0.07) +- (0.14,0.02)
};
\end{axis} 
\end{tikzpicture}

Here is what I get.

One workaround to remove exponentiation in the y-axis is to use the {semilogyaxis} with log ticks with fixed point option.

\begin{tikzpicture}
\begin{semilogyaxis} [log ticks with fixed point
,symbolic x coords={Lighting,Computers,Total},width=6.5cm]
\addplot+[only marks] plot[error bars/.cd, y dir=both, y explicit]
coordinates{
    (Lighting,0.12) +- (0.31,0.03)
    (Computers,0.06) +- (0.12,0.01) 
    (Total,0.07) +- (0.14,0.02)
};
\end{semilogyaxis} 
\end{tikzpicture}

Here is the output:

Edit

Here is another code snippet using the xtick=data,ytick=ydata option.

\begin{tikzpicture}
\begin{semilogyaxis} [log ticks with fixed point
,symbolic x coords={Lighting,Computers,Total},xtick=data,ytick=data]
\addplot+[only marks] plot[error bars/.cd, y dir=both, y explicit]
coordinates{
    (Lighting,0.12) +- (0.31,0.03)
    (Computers,0.06) +- (0.12,0.01) 
    (Total,0.07) +- (0.14,0.02)
};
\end{semilogyaxis} 
\end{tikzpicture}