PGFPlots – How to Format Significant Figures in TikZ

formattinggraphspgfplotstikz-pgf

I'm trying to work out how to change the number of sig figs in the axis labels. I.e., I want the graph to display 0.0, 1.0, etc. Any ideas?

\documentclass{memoir}
\usepackage{pgfplots}
\pgfplotsset{compat=1.8}

\begin{document}
\begin{tikzpicture}
% horizontal axis
\begin{axis}[xmin=0,xmax=50,ymin=0.0,ymax=4.0,grid=both,minor tick num=4, 
    major tick length=0pt,
    minor tick length=0pt,
    %no markers,
    ylabel=Applied Force/N,
    xlabel=Length/cm,
 every major grid/.style={black,opacity=0.8}]

 \addplot [black] coordinates  {
(0,0)
(8,0)
(38,3)};
 \end{axis}
\end{tikzpicture}

\end{document}

Best Answer

You can accomplish this by adjusting the style of whichever axis' tick labels you wish to adjust (xticklabel style, yticklabel style, or ticklabel style for both axes). Here I assume you wish to modify the y-axis tick labels.

The particular items of interest are

/pgf/number format/fixed zerofill (fixed format with trailing zeros shown) and
/pgf/number format/precision=1 (display one digit after the decimal separator).

Since these are both in the same "folder", we can save keystrokes by using .cd to switch into that folder.

Putting this all together, we have

yticklabel style={/pgf/number format/.cd,fixed zerofill,precision=1}

which can be added to the axis environment options.

Complete Code

\documentclass{memoir}
\usepackage{pgfplots}
\pgfplotsset{compat=1.8}

\begin{document}
\begin{tikzpicture}
% horizontal axis
\begin{axis}[xmin=0,xmax=50,ymin=0.0,ymax=4.0,grid=both,minor tick num=4, 
    major tick length=0pt,
    minor tick length=0pt,
    %no markers,
    ylabel=Applied Force/N,
    xlabel=Length/cm,
    yticklabel style={/pgf/number format/.cd,fixed zerofill,precision=1},
    every major grid/.style={black,opacity=0.8},
]

 \addplot [black] coordinates  {
(0,0)
(8,0)
(38,3)};
 \end{axis}
\end{tikzpicture}

\end{document}

Output

enter image description here

Related Solutions

[Tex/LaTex] “Pretty-printing” numbers with significant figures

To flesh-out an siunitx answer, you might do something like

\documentclass{article}

\usepackage{arrayjobx}
\newarray\MyData
\readarray{MyData}{ 3.14159 & 2077652 & 0.000006543 }

\usepackage{siunitx}
\sisetup{output-exponent-marker = E,round-mode = figures, round-precision = 3,
  scientific-notation = true}

\begin{document}

\checkMyData(1)
\num{\cachedata}

\checkMyData(2)
\num{\cachedata}

\checkMyData(3)
\num{\cachedata}

\end{document}

This needs siunitx v2.2, as the output-exponent-marker option is new. (I notice that this points up an issue with negative exponents when not using \times 10^{<exponent>}: I'll take a look at that over the next few days and see what I can do.)

PGFPlots – How to Hide Empty Ybars in Bar Charts

You can use

 y filter/.expression={y==0 ? nan : y}

in the options of \addplot.

\documentclass{article}

% ---------------------------------- tikz
\usepackage{pgfplots}          % to print charts
\pgfplotsset{compat=1.12}

\begin{document}

\begin{figure}
  \centering
  \begin{tikzpicture}
    \begin{axis} [
      % general
      ybar,
      scale only axis,
      height=0.5\textwidth,
      width=1.2\textwidth,
      ylabel={\# Dots},
      nodes near coords,
      xlabel={Variation},
      xticklabel style={
        rotate=90,
        anchor=east,
      },
      %enlarge x limits={abs value={3}},
      ]
      \addplot+[y filter/.expression={y==0 ? nan : y}] table [
        x=grade,
        y=value,
      ] {
grade   value
-11 0
-10 0
-9  0
-8  0
-7  0
-6  0
-5  3
-4  1
-3  2
-2  15
-1  11
0   179
1   8
2   1
3   0
4   1
5   2
6   0
7   0
8   0
9   0
10  0
11  0
      };
    \end{axis}
  \end{tikzpicture}
\end{figure}
\end{document}