or
Raaja
tikz
I have two curves sampled as shown below:


%&lualatex
% !TeX TXS-program:compile = txs:///lualatex/[--shell-escape]
\documentclass[convert={density=600,outext=.tiff}]{standalone}
\usepackage{tikz, pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[width=2in, height=2in,xmin = 0, xmax = 1050, ymin = 0, ymax = 10, ylabel = {[$\sim$]}, xlabel = {[\#]},legend style={at={(1,0)}, anchor=south east, font=\tiny, draw=none, fill=none}]	;
\addplot [mesh, domain = 0:1000,samples=300] {5*(1-exp(-0.003*x))};
\addplot [black, domain=0:1000, samples = 18, only marks, mark size = 1pt, mark = +] {5*(1-exp(-0.003*x))};
\addplot [black, domain=0:1100, samples = 18, only marks, mark size = 1pt, mark = +] {10 - 5*(1-exp(-0.003*x))};
\end{axis}
\end{tikzpicture}
\end{document}


I want to draw lines between the sampled data-points shown below:

![iwd.jpg](/image?hash=efae4baf3c987a997f0c4dcf9d7fb2e3685cd4c48cfd615a743133c95422f851)

But not sure how to achieve it.
marmot
Another way is to use nodes near coords.

\documentclass[tikz,convert={density=600,outext=.tiff}]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\pgfplotsset{% https://tex.stackexchange.com/a/75811/121799
name nodes near coords/.style={nodes near coords={},
every node near coord/.append style={anchor=center,coordinate,
name=#1-\coordindex,/utils/exec=\typeout{#1-\coordindex},
alias=#1-last,
},
},
name nodes near coords/.default=coordnode
}

\begin{document}
\begin{tikzpicture}
\begin{axis}[width=2in, height=2in,xmin = 0, xmax = 1050, ymin = 0, ymax = 10,
ylabel = {[$\sim$]}, xlabel = {[\#]},legend style={at={(1,0)}, anchor=south
east, font=\tiny, draw=none, fill=none},declare function={f(\x)=5*(1-exp(-0.003*\x));}]	;
\addplot [mesh, domain = 0:1000,samples=300] {f(x)};
\addplot [black, domain=0:1000, samples = 18, only marks, mark size = 1pt, mark=
+,name nodes near coords=T] {f(x)};
\addplot [black, domain=0:1100, samples = 18, only marks, mark size = 1pt, mark
= +,name nodes near coords=B] {10 -f(x)};
\end{axis}
\foreach \X in {0,...,16}
{\draw (B-\X) -- (T-\X);}
\end{tikzpicture}
\end{document}


![Screen Shot 2020-02-07 at 7.53.29 AM.png](/image?hash=482e506e2a903f21ce321a71ccb60db9bd7b6e581ac49476aad616c33b356798)

A potential problem is that the last mark on the upper plot gets clipped away, and thus not connected.
samcarter
Not very elegant, but worst case you could add the lines manually:


\documentclass{standalone}
\usepackage{tikz, pgfplots}

\tikzset{
declare function={
f(\x)=(5*(1-exp(-0.003*\x))));
}
}

\begin{document}
\begin{tikzpicture}
\begin{axis}[width=2in, height=2in,xmin = 0, xmax = 1050, ymin = 0, ymax = 10, ylabel = {[$\sim$]}, xlabel = {[\#]},legend style={at={(1,0)}, anchor=south east, font=\tiny, draw=none, fill=none}]	;
\addplot [mesh, domain = 0:1000,samples=300] {f(x)};
\addplot [black, domain=0:1000, samples = 18, only marks, mark size = 1pt, mark = +] {f(x)};
\addplot [black, domain=0:1100, samples = 18, only marks, mark size = 1pt, mark = +] {10 - f(x)};
\foreach \i in {0,...,18}{
}
\end{axis}
\end{tikzpicture}
\end{document}


![document.png](/image?hash=0c6ebc3619dcb621e8d5a64014e3f9650072622bc77cae289f1dffbef7dd9bd3)
Drawing straight lines between sampled curves
Raaja
@samcarter I dont think he did.
I clicked on the comment link below his answer. Is he not notified about comments to his answer?
@samcarter did you ping @marmot wrongly ;)
@marmot Very clever!
cool!
connecting top and bottom + based on the slope ;)
Should the lines be vertical or should the lines connect the +, be inclined a bit?@Raaja