I would like to draw a vector field from a data file. I tried to adapt code from Manual for Package pgfplots but this doesn't work
\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotstableread{vector_field.dat}{\loadedtable}
\begin{document}
\begin{tikzpicture}
\begin{axis}[title=Quiver and plot table]
\addplot[blue,quiver={u=\thisrow{u},v=\thisrow{v}},-stealth] table from \loadedtable;
\end{axis}
\end{tikzpicture}
\end{document}
where data file vector_field.dat is :
x y u v
0 0 1 0
1 1 1 1
2 4 1 4
3 9 1 6
4 16 1 8
During compilation I get for example this error:
! Undefined control sequence.
\pgfk@/data point/quiver/u ->\thisrow
{u}
l.8 ...row{v}},-stealth] table from \loadedtable;
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.
! Package PGF Math Error: Unknown function `u' (in '{u}').
Does anyone now how to solve it? I would be grateful for any help.
Best Answer
I get the error message
! Package PGF Math Error: Unknown function `thisrow_unavailable_load_table_directly'
. If I do that, that is, if I use\addplot ... table {vector_field.csv};
, the document compiles: