Specific arrow tip style for specific path

\documentclass[12pt]{article}
\usepackage{tikz}
\usetikzlibrary{decorations.markings}

\begin{document}

\begin{tikzpicture}[scale=1.5,cap ,color= blue]

% grid
\draw[very thin,color = green,step = 0.5 cm, opacity= 0.9](0,0) grid (4, 4);

% axis
\draw[->]  [blue,  thick] ( 0,0) --( 4,0) node[right] {$x$};
\draw[->]  [blue,  thick] ( 0,0) --( 0,4) node[above] {$y$};
% how to change the arrow tip style at specific path
% how to set up unique arrow head as a decoration at (1,0) coordinate and at (0,1)
\draw[decoration={markings, mark=at position 0.5 with {\arrow [ ultra thick] {>}}},
postaction={decorate}]
(0,0)--( 2,0);
\draw[decoration={markings, mark=at position 0.5 with {\arrow [ ultra thick] {>}}},
postaction={decorate}]
(0,0)--( 0,2);
\end{tikzpicture}
\end{document}

• Please reduce the title and add some explanations to the post, e.g. a sketch or screen shot of what you want to achieve. A tip: If you indent lines by 4 spaces or enclose words in backticks , they'll be marked as code, as can be seen in my edit. You can also highlight the code and click the "code" button (with "{}" on it). – user31729 Aug 4 '14 at 7:17

You can replace the > with the desired type of arrow. Below I used the latex and stealth type of arrow in the first image. Alternatively, you can leave the > and apply \tikzset{>=latex} which will replace all > with a latex style arrow as in the second image:

Code:

\documentclass[12pt]{article}
\usepackage{tikz}
\usetikzlibrary{decorations.markings}
\tikzset{>=latex}

\begin{document}

\begin{tikzpicture}[scale=1.5,cap=0.5 ,color= blue]

% grid
\draw[very thin,color = green,step = 0.5 cm, opacity= 0.9](0,0) grid (4, 4);

% axis
\draw[->]  [blue,  thick] ( 0,0) --( 4,0) node[right] {$x$};
\draw[->]  [blue,  thick] ( 0,0) --( 0,4) node[above] {$y$};
% how to change the arrow tip style at specific path
% how to set up unique arrow head as a decoration at (1,0) coordinate and at (0,1)
\draw[decoration={markings, mark=at position 0.5 with {\arrow [ ultra thick] {latex}}},
postaction={decorate}]
(0,0)--( 2,0);
\draw[decoration={markings, mark=at position 0.5 with {\arrow [ ultra thick] {stealth}}},
postaction={decorate}]
(0,0)--( 0,2);
\end{tikzpicture}
%
\begin{tikzpicture}[scale=1.5,cap=0.5 ,color= blue]

% grid
\draw[very thin,color = green,step = 0.5 cm, opacity= 0.9](0,0) grid (4, 4);

% axis
\draw[->]  [blue,  thick] ( 0,0) --( 4,0) node[right] {$x$};
\draw[->]  [blue,  thick] ( 0,0) --( 0,4) node[above] {$y$};
% how to change the arrow tip style at specific path
% how to set up unique arrow head as a decoration at (1,0) coordinate and at (0,1)
\draw[decoration={markings, mark=at position 0.5 with {\arrow [ ultra thick] {>}}},
postaction={decorate}]
(0,0)--( 2,0);
\draw[decoration={markings, mark=at position 0.5 with {\arrow [ ultra thick] {>}}},
postaction={decorate}]
(0,0)--( 0,2);
\end{tikzpicture}
\end{document}

• As a MWE this works. This is one of the include files. However, this is a book, so before \front matter, I have a list of usetikzlibrary. Now I had a code "\tikzset{>=latex} . This gives a standardised arrow throughout every tikzpicture drawn. It does not typeset into desired tip. Kindly advise what I don't understand or missed out. – mark Aug 4 '14 at 8:50
• @mark: Have updated solution to show that using \tikzset{>=latex}` does indeed work. IF that still does not work, please update your question with a MWE that reproduces the problem. – Peter Grill Aug 4 '14 at 16:17