# How to Draw Multiple Y-Axis in Latex PGFPlots

Sometimes, we need to plot two or three line charts in the same plot due to lack of space. Also, if we need to plot three different y-axis against the same x-axis, it is better we put all three in a single plot diagram.

Now, thw question is why we might need different scales! Why don’t we use the same y-axis for all!

The answer is, you may not find the plots meaningful if there is large gaps between the ranges of y-axis values. If ranges are very small and very distant, you may find several straight lines in your plot. That’s why we need to use different y-axis for plotting different lines.

In this post, I adapt the codes from two stack overflow threads (links in the reference section) and provide the code for 2- and 3-y axis plots. You can find the outputs in this Overleaf Project.

## Required Packages

\usepackage{pgfplots}
\usepackage{pgfplotstable}
\pgfplotsset{compat=1.7}
\usepackage{subcaption}


## Multiple Axis in PGFPlot

### Two y-axis

\begin{figure}
\centering
\begin{tikzpicture}
\pgfplotsset{
scale only axis,
scaled x ticks=base 10:3,
xmin=0, xmax=0.06,
y axis style/.style={
yticklabel style=#1,
ylabel style=#1,
y axis line style=#1,
ytick style=#1
}
}

\begin{axis}[
axis y line*=left,
y axis style=blue!75!black,
ymin=0, ymax=80,
xlabel=$x\_label$,
ylabel=$y\_label\_1$
]
coordinates{
(0,68.6)
(0.0148,72)
(0.0295,68.6)
(0.0441,53.4)
(0.059,22.8)
};
\end{axis}

\begin{axis}[
axis y line*=right,
axis x line=none,
ymin=0, ymax=100,
ylabel=$y\_label\_2$,
y axis style=red!75!black
]
coordinates{
(0,0)
(0.0148,48)
(0.0295,66)
(0.0441,66)
(0.059,45.0)
};
\end{axis}

\end{tikzpicture}
\caption{PGFplot Code for two y-Axis}
\label{fig:pgfplot-two}
\end{figure}


### Three y-axis

\begin{figure}
\centering

\begin{tikzpicture}
\pgfplotsset{every axis/.style={ymin=0},
y axis style/.style={
yticklabel style=#1,
ylabel style=#1,
y axis line style=#1,
ytick style=#1}}
\begin{axis}[ scale only axis, xmin=0,xmax=12, axis y line*=left, xlabel=fractions, ylabel=Small Axis (green), y axis style=green!75!black]
\addplot[smooth, green!75!black, mark=o, draw] coordinates {(0,0)
(1,0.3)(2,0.4)
(3,0.6)(4,0.7)
(5,1)(6,1.4)
(7,1.3)(8,1.1)
(9,0.7)(10,0.6)
(11,0.5)(12,0.4)};
\end{axis}
%
\begin{axis}[ scale only axis, xmin=0,xmax=12, axis y line*=right, axis x line=none, ylabel=Second ordinate (blue), y axis style=blue]%
(1,2)(2,6)
(3,10)(4,20)
(5,18)(6,15)
(7,12)(8,10)
(9,8)(10,7)
(11,6)(12,5)};
\end{axis}
%
\begin{axis}[red, scale only axis, xmin=0,xmax=12, axis y line*=right, axis x line=none, ylabel=third ordinate (red)]%
\pgfplotsset{every outer y axis line/.style={xshift=2cm}, every tick/.style={xshift=2cm}, every y tick label/.style={xshift=2cm} }
(1,6)(2,8)
(3,9)(4,13)
(5,18)(6,29)
(7,40)(8,50)
(9,38)(10,27)
(11,23)(12,10)};
\end{axis}

\end{tikzpicture}
\caption{PGFplot Code for three y-Axis}
\label{fig:pgfplot-three}
\end{figure}


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