Recently I found a great example provided by the community of Stack Exchange where fillbetween
was used to fill the area between a curve and a constant (see 1st image). I liked it especially, since the color of the area changes depending on whether the curve is larger or smaller than the constant. This was made possible by a findintersections
function provided by Jake (link to solution). However, I think it would be especially useful if it would fill an area between two curves (see 2nd image). I have provided a MWE below, which has two curves and a constand. Could somebody provide a solution where the two curves are compared against one another. Then based on which is larger than the other, change the colour between the curves? I think doing this would be very useful for graphs which are otherwise hard to interpret, where differences between two curves are small and there is much overlap.
MWE:
\documentclass{article}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\usepackage{filecontents}
\usetikzlibrary{calc}
\begin{filecontents}{data.dat}
0 0.2
1 0.217
2 0.255
3 0.288
6 0.58
7 0.91
8 1.02
10 1.05
12 0.92
13 0.78
15 0.56
17 1.1
\end{filecontents}
\begin{filecontents}{data2.dat}
0 1.2
1 0.8
2 0.6
3 0.20
6 0.4
7 0.5
8 1.5
10 1.5
12 0.5
13 0.9
15 0.4
17 1.1
\end{filecontents}
\pgfplotstableread{data.dat}\data
\pgfplotstableread{data2.dat}\datas
\newcommand\findintersections[2]{
\def\prevcell{#1}
\pgfplotstableforeachcolumnelement{1}\of#2\as\cell{%
\pgfmathparse{!or(
and(
\prevcell>#1,\cell>#1
),
and(
\prevcell<#1,\cell<#1
)
)}
\ifnum\pgfmathresult=1
\pgfplotstablegetelem{\pgfplotstablerow}{0}\of{\data} \let\xb=\pgfplotsretval
\pgfplotstablegetelem{\pgfplotstablerow}{1}\of{\data} \let\yb=\pgfplotsretval
\pgfmathtruncatemacro\previousrow{ifthenelse(\pgfplotstablerow>0,\pgfplotstablerow-1,0)}
\pgfplotstablegetelem{\previousrow}{0}\of{\data} \let\xa=\pgfplotsretval
\pgfplotstablegetelem{\previousrow}{1}\of{\data} \let\ya=\pgfplotsretval
\pgfmathsetmacro\newx{
\xa+(\ya-#1)/(ifthenelse(\yb==\ya,1,\ya-\yb) )*(\xb-\xa) }
\edef\test{\noexpand\pgfplotstableread[col sep=comma,row sep=crcr,header=has colnames]{
0,1\noexpand\\
\newx,#1\noexpand\\
}\noexpand\newrow}
\test
\pgfplotstablevertcat\interpolated{\newrow}
\fi
\let\prevcell=\cell
}
\pgfplotstablevertcat\interpolated{#2}
\pgfplotstablesort[sort cmp={float <}]\interpolated{\interpolated}
\pgfplotstableset{
create on use/above line/.style={
create col/expr={max(\thisrow{1},#1)}
},
create on use/below line/.style={
create col/expr={min(\thisrow{1},#1)}
},
}
}
\begin{document}
\pgfplotsset{compat=newest} % For nicer label placement
\findintersections{0.9}{\data}
\begin{tikzpicture}
\begin{axis}[
xlabel=Time of day,
ylabel=Volume,
ytick=\empty,
axis x line=bottom,
axis y line=left,
enlargelimits=true
]
\addplot[fill,gray!20!white,no markers,line width=2pt] table [y=above line] {\interpolated} |- (current plot begin);
\addplot[fill,yellow!20!white,no markers,line width=2pt] table [y=below line] {\interpolated} |- (current plot begin);
\addplot[orange,no markers,line width=2pt,domain=-1:20] {0.9};
\addplot[blue,line width=2pt,mark=*] table {\data};
\addplot[red,line width=2pt,mark=*] table {\datas};
\end{axis}
\end{tikzpicture}
\end{document}