# Styling a particular y tick on tikz plot

I want to change the style of a single y axis tick mark. The y-axis is for a car's speed in mph, and I want the speed limit to be a single bold line. I currently have major, and minor ticks set up. I have 2 ticks (speed limit & speed limit *2) for the major ticks and is styled bold, and the minor ticks have the speeds in between the two. The issue arises when a person does more then twice the speed limit and goes off the chart (the ymax value is set to the speed limit *2). I am making the .tex documents in bulk via a c program, so I cannot hand edit each chart for the occurrences. I would assume there is a way in order to style a single tick differently, or adding a separate horizontal line on the chart to represent the speed limit. Let me know if you need anymore information.

Here's the chart that I am making:

\begin{document}
\begin{tikzpicture}
\begin{axis}
[
title = Peak vs. Average Speeds,
enlarge x limits = 0.03,
ymin = 0,
ymax = 50,    %This is controlled by speed limit *2
ybar = 0pt,
ylabel=Speed (mph),
ymajorgrids = true,
yminorgrids = true,
minor y tick num = {4},
ytick = {0, 25, 50},
ytick pos = left,
extra y tick style = {major grid style = {line width = 0.1pt, draw=gray!}},

% These tick labels are generated by a loop being controlled by the speed limit. It would be great if I didn't need it.
extra y tick labels = {5, 10, 15, 20, 30, 35, 40, 45},
extra y ticks = {5, 10, 15, 20, 30, 35, 40, 45},
symbolic x coords = {00:00, 00:30, 01:00, 01:30, 02:00, 02:30, 03:00, 03:30, 04:00, 04:30, 05:00, 05:30, 06:00, 06:30, 07:00, 07:30, 08:00, 08:30, 09:00, 09:30, 10:00, 10:30, 11:00, 11:30, 12:00, 12:30, 13:00, 13:30, 14:00, 14:30, 15:00, 15:30, 16:00, 16:30, 17:00, 17:30, 18:00, 18:30, 19:00, 19:30, 20:00, 20:30, 21:00, 21:30, 22:00, 22:30, 23:00, 23:30, 24:00},
x axis line style = {line width = 1pt},
xtick pos = left,
xtick = {00:00, 02:00, 04:00, 06:00, 08:00, 10:00, 12:00, 14:00, 16:00, 18:00, 20:00, 22:00, 24:00},
minor x tick num = {3},
major grid style = {line width = 0.6pt, draw = black!},
minor grid style = {line width = 0.1pt, draw = gray!},
bar width = 3pt,
width = 7in,
height = 4.25in,
legend pos = north west
]
\addplot table[x=Time, y=Peak Speed, col sep = comma] {Peak_and_Average_Speeds.csv};
\addplot table[x=Time, y=Average Speed, col sep = comma] {Peak_and_Average_Speeds.csv};
\legend{Peak Speed, Average Speed};
\end{axis}
\end{tikzpicture}


• It would be helpful to show us what you have tried. Posting a minimal working example that indicates what you are trying to do makes it easier for people to understand what you want. It also makes it easier for people to help you, since they have some code to start from, and much more likely that some one will try to help you. – Andrew Oct 19 '16 at 2:27

Since you want the graph limits to come from the data, let pgfplots set the tick marks/grid lines itself. Just draw darker lines over the top.

One way to get the speed limit info is to write a file containing \def\limit{25} or even just 25. Alternatively, you could add it to one of the tables as a third column and read it using \pgfplotstableread and \pgfplotstablegetelem.

\documentclass{standalone}
\usepackage{pgfplots}

\begin{document}

% the following can be either inside or outside the tikzicture
\def\limit{25}% speed limit, possibly read using \input{file}
\pgfmathsetmacro{\double}{int(2*\limit)}%

\begin{tikzpicture}
\begin{axis}[
title = Peak vs. Average Speeds,
enlarge x limits = 0.03,
ymin = 0,
ybar = 0pt,
ymajorgrids=true,
major grid style = {line width = 0.1pt, draw = gray!},
ylabel=Speed (mph),
ytick distance=5,
ytick pos = left,
ytick style={opacity=0},% otherwise, zooming in will reveal ticks on top of the grid lines
symbolic x coords = {00:00, 00:30, 01:00, 01:30, 02:00, 02:30, 03:00, 03:30, 04:00, 04:30, 05:00, 05:30, 06:00, 06:30, 07:00, 07:30, 08:00, 08:30, 09:00, 09:30, 10:00, 10:30, 11:00, 11:30, 12:00, 12:30, 13:00, 13:30, 14:00, 14:30, 15:00, 15:30, 16:00, 16:30, 17:00, 17:30, 18:00, 18:30, 19:00, 19:30, 20:00, 20:30, 21:00, 21:30, 22:00, 22:30, 23:00, 23:30, 24:00},
x axis line style = {line width = 1pt},
xtick pos = left,
xtick = {00:00, 02:00, 04:00, 06:00, 08:00, 10:00, 12:00, 14:00, 16:00, 18:00, 20:00, 22:00, 24:00},
minor x tick num = {3},
bar width = 3pt,
width = 7in,
height = 4.25in,
legend pos = north west
]
\coordinate (sw) at (rel axis cs: 0,0);% lower left corner of axis box
\coordinate (ne) at (rel axis cs: 1,1);% upper right corner of axis box
\coordinate (limit) at (axis cs: 00:00,\limit);% any x coord will do
\coordinate (double) at (axis cs: 00:00,\double);
\draw[black,line width = 0.6pt] (sw|-limit) -- (ne|-limit) (sw|-double)--(ne|-double);
%\addplot table[x=Time, y=Peak Speed, col sep = comma] {Peak_and_Average_Speeds.csv};
%\addplot table[x=Time, y=Average Speed, col sep = comma] {Peak_and_Average_Speeds.csv};
\addplot coordinates {(00:00,10) (24:00,65)}; % replace unavailable tables
\legend{Peak Speed, Average Speed};
\end{axis}
\end{tikzpicture}
\end{document}


• The issue is when someone goes over double the speed limit, lets just say 70mph. They go off the chart. The only reason why I have a ymax set is so that I can style the 25, or what ever the speed limit is, to be bold as a major ticks. I want to get rid of the ymax option to let the max be made based off of the data. – techdude1996 Oct 19 '16 at 20:30
• Actually, it is much easier this way. – John Kormylo Oct 20 '16 at 4:11