[Tex/LaTex] pgfplot | tikzpicture | changing length + width of ticks

pgfplotstickstikz-pgf

While there are any number of posts on how to fiddle (from the Latin) with tick labels, or tick placements, or tick color, I haven't been able to find anything (in terms of worked examples, or in the documentation), for how to change the length and width of the ticks themselves. Perhaps I simply haven't found the right search phrase(s).

At any rate, the question probably doesn't need an MWE, but to provide one for a simple 'answer by demonstration', here is a simple plot where I'd like to decrease the length (distance from top of tick mark to axis) by (say) 50%, relative to the default length. Thanks much in advance. 

\documentclass{article}
\usepackage{pgfplots}

\begin{document}

\begin{tikzpicture}
    \begin{axis}
      [width=190pt,axis x line=middle, axis y line=center, 
      tick align=outside,
      xmin=0.3,xmax=7.7,ymin=0.44,ymax=1.05,
      xlabel={\emph{x-axis label}},ylabel={\emph{y-axis label}},
      xtick={1,2,3,4,5,6,7},ytick={0.5,0.6,0.7,0.8,0.9,1.0},
      x label style={at={(axis description cs:0.5,-0.1)},anchor=north},
      y label style={at={(axis description cs:-0.1,.5)},rotate=90,anchor=south},
      every tick/.style={black,semithick,height=1cm},
      ylabel style={yshift=0.2cm}, xlabel style={yshift=-0.2cm}]
        \addplot+[mark=none,smooth, thick]  plot coordinates {
            (1,1)
            (2,0.75)
            (3,0.666)
            (4,0.625)
            (5,0.6)
            (6,0.5833)
            (7,0.571)
        };
        \addplot [red, dashed, no markers, thick] coordinates {(0.3,0.5) (7.7,0.5)};
    \end{axis}
\end{tikzpicture}
\end{document}

Best Answer

The tick length can be configured with option major tick length (or the alias tickwidth. Minor ticks are configured with option minor tick length (or subtickwidth). In this case, we have major ticks only. The default is 0.15cm and can be derived by \pgfkeysvalueof{/pgfplots/major tick length}. I found the option names in section "4.15.4 Tick Fine-Tuning" of the manual of pgfplots.

Example, which sets the tick length to 50 % of the default:

\documentclass{article}
\usepackage{pgfplots}
%\pgfplotsset{compat=1.12}

\begin{document}
\begin{tikzpicture}
    \pgfmathsetlengthmacro\MajorTickLength{
      \pgfkeysvalueof{/pgfplots/major tick length} * 0.5
    }
    \begin{axis}[ 
      width=190pt,
      axis x line=middle,
      axis y line=center,
      tick align=outside,
      xmin=0.3, 
      xmax=7.7, 
      ymin=0.44,
      ymax=1.05,
      xlabel={\emph{x-axis label}},
      ylabel={\emph{y-axis label}},
      xtick={1,2,3,4,5,6,7},
      ytick={0.5,0.6,0.7,0.8,0.9,1.0},
      x label style={
        at={(axis description cs:0.5,-0.1)},
        anchor=north,
      },
      y label style={
        at={(axis description cs:-0.1,.5)},
        rotate=90,   
        anchor=south,
      },
      major tick length=\MajorTickLength,
      every tick/.style={
        black,
        semithick,
      },
      ylabel style={yshift=0.2cm},
      xlabel style={yshift=-0.2cm}
    ]
        \addplot+[mark=none,smooth, thick]  plot coordinates {
            (1,1)     
            (2,0.75)  
            (3,0.666) 
            (4,0.625) 
            (5,0.6)   
            (6,0.5833)
            (7,0.571)
        };
        \addplot [red, dashed, no markers, thick] coordinates {(0.3,0.5)
        (7.7,0.5)};
    \end{axis}   
\end{tikzpicture}
\end{document}

Result

Bold tick numbers

This is an answer to CroCo's comment and to Dr. Manuel Kuehner's comment.

Bold tick numbers can be set via option tick label style. Since the tick numbers are set in math mode by default (see \axisdefaultticklabel), \boldmath gets bold tick numbers.

Key tick label style appends to every tick/.style, thus the following updated example (using pgfplots 1.17) merges the two keys:

\documentclass{article}
\usepackage{pgfplots}
\pgfplotsset{compat=1.17}

\begin{document}
\begin{tikzpicture}
    \pgfmathsetlengthmacro\MajorTickLength{
      \pgfkeysvalueof{/pgfplots/major tick length} * 0.5
    }
    \begin{axis}[
      width=190pt,
      axis x line=middle,
      axis y line=center,
      tick align=outside,
      xmin=0.3,
      xmax=7.7,
      ymin=0.44,
      ymax=1.05,
      xlabel={\emph{x-axis label}},
      ylabel={\emph{y-axis label}},
      xtick={1,2,3,4,5,6,7},
      ytick={0.5,0.6,0.7,0.8,0.9,1.0},
      x label style={
        at={(axis description cs:0.5,-0.1)},
        anchor=north,
      },
      y label style={
        at={(axis description cs:-0.1,.5)},
        rotate=90,
        anchor=south,
      },
      major tick length=\MajorTickLength,
      ylabel style={yshift=0.2cm},
      xlabel style={yshift=-0.2cm},
      tick label style={black, semithick, font=\boldmath},
    ]
        \addplot+[mark=none,smooth, thick]  plot coordinates {
            (1,1)
            (2,0.75)
            (3,0.666)
            (4,0.625)
            (5,0.6)
            (6,0.5833)
            (7,0.571)
        };
        \addplot [red, dashed, no markers, thick] coordinates {(0.3,0.5)
        (7.7,0.5)};
    \end{axis}
\end{tikzpicture}
\end{document}

Result with bold tick numbers

Related Question