Circling/framing and referring to a bunch of nodes

Question

The end goal: drawing paths between nodes like in the example there but the difference is the nodes are inside a picture here and in particular, the other node is a bunch of nodes in the same picture. So a minor goal is to be able to refer to some nodes as a whole.

My first attempt was just to wrap the said bunch of nodes in a big node but bizarrely, that didn't work ;). So I had a look at

1. How to typeset a TikZ picture inside a node?
2. How to nest a graph within a node in TikZ and draw edges between the graphs?

but I still have problems. See the related questions, in particular Q5-Q8 in the example code below. I tried two approaches, the preferred approach would be the one called first try below but that didn't work (Q5). The second approach (using the fit library) is close to what I want but there are still a few flaws left (Q6-Q8).

\documentclass{minimal}

\usepackage{tikz}
\usetikzlibrary{arrows,shapes,fit}

\begin{document}

\tikzstyle{every picture}+=[remember picture]

\begin{tikzpicture}[scale=1.4]

  \begin{scope}[>=stealth]
    %% Timeline
    \draw (0,0) -- (2.2,0);%
    \draw[loosely dotted] (2.5,0) -- (3.5,0);%
    %%% Q1: In fact, it would have been great if I could just position
    %%% the second part of the graph after the continuation dots in
    %%% the next scope. See Q4
    \draw (3.8,0) -- (7.2,0);%
    \draw[loosely dotted] (7.2,0) -- (7.5,0);%
    \draw[->] (7.5,0) -- (7.7,0);%
    %%% Q2: Is it possible to use calc or something else to just say 5/N+\x-4 
    \foreach \x/\xtext in {0,...,2,4/N,5/N+1,6/N+2,7/N+3} {%
      \draw[shift={(\x,0)}] (0, +0.2) -- (90:0);%
      %%% Q3: How do I put this above the tick without manually
      %%% setting 0.3? I'm not sure the draw command allows to write
      %%% beyond the path ... 
      \node at (\x,0.3) {$\xtext$};%
    }
  \end{scope}

  \begin{scope}[>=stealth]
    %%% Q4: In fact, I wish I could just say continue at any point,
    %%% say 3.5 and just start at 1 instead of 4 in this scope. Is
    %%% there a way to say this scope should start at 3.5 in the
    %%% current picture?
    \draw[shift={(4,0)}] (0,0) -- %
    node[very near end,right] {$Div_N$} +(90:-0.2);%
    \node[right,fill=red!15,baseline] (continuation) at (4,-0.5) {$+
      P_N$};%

    % ### First try
    %%% It's really what I want to do but I can't succeed in
    %%% positioning precisely the nested tikzpicture environment.
    %%% Q5: What's going wrong here?
    % % Maturity phase
    % \node[right,fill=red!15] (maturity) at (5,0) {
    %   \begin{tikzpicture}
    %     \draw[shift={(5,0)}] (0,0) -- %
    %     node[very near end,right] (5) {$Div_{N+1}$} +(90:-0.2);%
    %     \foreach \x/\xtext in {6/(1+g),7/(1+g)^2} {%
    %       \draw[shift={(\x,0)}] (0,0) -- %
    %       node[very near end,right] {$Div_{N+1}$} +(90:-0.2);%
    %       \node[right] (\x) at (\x,-0.5) {$\times \xtext$};%
    %     }
    %   \end{tikzpicture}
    %   };
    % ### Alternative solution with the fit library.
    %%% It's very close to the end result but 3 problems here:
    %%% Q6: Even playing with the opacity, I can't get the same thing
    %%% as with the (continuation) node: I can't see the text as well.
    %%% Q7: Adding the inner sep option (see why in Q8) gives
    %%% underfull \hbox warning???
    %%% Q8: But much worse is the fact that if I get rid of the
    %%% ellipse and the inner sep options, the rectangular draw
    %%% doesn't include the first $Div_{N+1}$ perfectly
    % Maturity phase
    \draw[shift={(5,0)}] (0,0) -- %
    node[very near end,right] (5) {$Div_{N+1}$} +(90:-0.2);%
    \foreach \x/\xtext in {6/(1+g),7/(1+g)^2} {%
      \draw[shift={(\x,0)}] (0,0) -- %
      node[very near end,right] {$Div_{N+1}$} +(90:-0.2);%
      \node[right] (\x) at (\x,-0.5) {$\times \xtext$};%
    }
    \node[fill=red!15,fill
    opacity=0.5,anchor=base,thick,ellipse,fit=(5)(6)(7),inner
    sep=3.5pt] (maturity) {};%
  \end{scope}

  %%% Link both parts
  \begin{scope}[overlay,>=stealth,very thick,red!15]
    \path[->] (maturity) edge [bend left] (continuation);
  \end{scope}

\end{tikzpicture}

\end{document}

Answer 1

(Note: You ask too many questions in one!)

Some remarks:

• Don't use scale with the fit library !
• ellipse fits the bounding box of its content, so it always seems too high.
• You can use the backgrounds library to put something below existing content.

Here is a global answer:

\documentclass[margin=1mm]{standalone}

\usepackage{tikz}
\usetikzlibrary{shapes,backgrounds,fit,positioning}

\begin{document}
\begin{tikzpicture}[x=1.4cm]
    % all points
  \foreach \x in {0,...,7}{
    \coordinate (pt \x) at (\x,0);
  }

  % add ticks and labels
  \foreach \x\xtext in {0/0,1/1,2/2,4/N,5/N+1,6/N+2,7/N+3}{
    \path (pt \x) node[above=3mm] (tick) {$\xtext$};%
    \draw (pt \x) -- (tick);
  }

  % draw axe
  \foreach \x in {0,1,4,5,6}{
    \pgfmathtruncatemacro{\xnext}{\x+1};
    \draw (pt \x) -- (pt \xnext);
  }
  % first dotted hole
  \draw (pt 2) -- +(.2,0);
  \draw[loosely dotted] (pt 2) ++(.5,0) -- ++(1,0);
  \draw (pt 2) ++(1.8,0) -- (pt 4);
  % second dotted hole
  \draw (pt 7) -- ++(.2,0);
  \draw[loosely dotted] (pt 7) ++(.2,0) -- ++(.3,0);
  \draw[-stealth] (pt 7) ++(.5,0) -- ++(.2,0);

  % add formulas
  \foreach \x/\form/\subform in {%
    4/$Div_{N}$/$+P_N$,%
    5/$Div_{N+1}$/,%
    6/$Div_{N+1}$/$\times(1+g)$,%
    7/$Div_{N+1}$/$\times(1+g)^2$}{%
    \path (pt \x)
    node[below=3mm,anchor=north,inner sep=0] (form \x) {\form};
    \node[below=1pt of form \x.south west,anchor=north west,inner sep=0]
    (subform \x){\subform};
    \draw (pt \x) -- (form \x);
  }

  % red ellipse and rectangle
  \begin{scope}[on background layer]
    \node[rounded corners,fit=(form 5.north west)(subform 7),inner sep=2pt,
    fill=red!15] (rr) {};
    \node[rounded corners,fit=(subform 4),inner sep=2pt,
    fill=red!15] (r4) {};
    \draw[-stealth,red!15,very thick] (rr) to[bend left=30] (r4);
  \end{scope}
\end{tikzpicture}
\end{document}