Is there an "out of the box" way to automatically draw the trend line in pgfplots?
Below follows a basic illustration of a scatter graph with a line of best fit:
asked Feb 16, 2011 at 20:16
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5For a linear regression see Section 4.22 of the pgfplots manual.– Thorsten DonigCommented Feb 16, 2011 at 20:21
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Of course, how could I have missed that? Didn't find anything in the scatter plot section.– Milo WielondekCommented Feb 16, 2011 at 20:25
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Not out of the box, but pgfplots can call gnuplot and you can create a simple script to fit an arbitrary function to your points. This might be more flexible depending on your dataset– Martin HCommented Feb 16, 2011 at 20:29
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I've always gone with doing the fit myself, then plotting the line using two endpoints (so I can, for example, fix the intercept). Not very elegant, but it works ...– Joseph Wright ♦Commented Feb 16, 2011 at 20:31
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2Some time back I made a little example on how to fit with pgfplots+gnuplot dl.dropbox.com/u/15487093/gnuplot-fit.tex– Martin HCommented Feb 16, 2011 at 20:35
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1 Answer
Can be achieved using
/pgfplots/table/create col/linear regression={⟨key-value-config⟩}
documented in Section 4.22 of the pgfplots manual.
Here's a slightly adapted version of the example from the manual. If you want to plot data directly from a file, replace the \datatable in the \addplot command with the file name.
\documentclass{standalone}
\usepackage{pgfplots, pgfplotstable}
\pgfplotstableread{
X Y
1 1
2 4
3 9
4 16
5 25
6 36
}\datatable
\begin{document}
\begin{tikzpicture}
\begin{axis}[legend pos=outer north east]
\addplot [only marks, mark = *] table {\datatable};
\addplot [thick, red] table[
y={create col/linear regression={y=Y}}
] % compute a linear regression from the input table
{\datatable};
\addlegendentry{$y(x)$}
\addlegendentry{%
$\pgfmathprintnumber{\pgfplotstableregressiona} \cdot x
\pgfmathprintnumber[print sign]{\pgfplotstableregressionb}$}
\end{axis}
\end{tikzpicture}
\end{document}
answered Feb 16, 2011 at 20:28