Can a scope environment behave like a node?

Question

The following flowchart was made in PowerPoint, and it describes the input and output of a function.

As you can see, the diagram is quite intuitive: a set of files are piped into "Function", and it returns a data structure "Struct".

I am trying to draw it using TikZ.

My approach was to draw the first two blocks using nodes and then create the "Struct" shape using a node and a bunch of lines inside a scope environment, so that the node and the lines remain grouped together as a single shape.

I managed to draw and connect the first two blocks. However, I am having trouble to place and connect the "Struct" shape in the diagram. I was expecting that the scope environment would behave like a node, and gave this instruction:

\begin{scope}[right of=function]

But this is what I got:

• Is it possible to make scope environment behave like a node?
• If so, how can I accomplish this?
• Otherwise, what alternatives do I have?

---

Code:

\documentclass[border=5pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{
    shapes.geometric,
    arrows,
    shadows
}
\usepackage{varwidth}
\usepackage{enumitem}
\usepackage{courier}

\renewcommand*\familydefault{\ttdefault}

\begin{document}

\begin{tikzpicture}[node distance=5cm]
  \tikzset{
    files/.style = {
        rectangle,
        fill=white,
        draw=black,
        minimum width=3cm,
        minimum height=1.5cm
        },
    function/.style = {
        rectangle,
        fill=white,
        draw=black,
        minimum width=3cm,
        minimum height=1.5cm,
        text centered
        },
    box/.style = {
            rectangle,
            fill=white,
            draw=black,
            minimum width=2cm,
            minimum height=0.5cm
        },
    arrow/.style={
        ->,
        >=latex,
        },
  }

  % Input
  \node (files) [files, drop shadow] {
            \begin{varwidth}{3cm}
            \begin{itemize}[noitemsep, leftmargin=*]
            \item{file1.dat}
            \item{file2.dat}
            \item{file3.dat}
            \item{file4.dat}
            \end{itemize}
            \end{varwidth}
  };

  % Function
  \node (function) [function, right of=files, drop shadow] {Function};

  % Output
  \begin{scope}[right of=function]
        \draw (0,0) -- (0,1) node[above, box, drop shadow] {Struct};
        \draw (-1.5,-1) -- (-1.5,0) -- (1.5,0) -- (1.5,-1);
        \draw (-0.5,-1) -- (-0.5,0);
        \draw (0.5,-1) -- (0.5,0);
  \end{scope}

  % Arrows
  \draw [arrow] (files) -- (function);
\end{tikzpicture}

\end{document}

Answer 1

You can use a local bounding box declaration to name the collective contents of the scope. In order for this to work in this case, the most straightforward strategy is to draw the stuff in the scope first.

For example (updating the code a little along the way e.g. to use arrows.meta and positioning as recommended):

\documentclass[tikz,multi,border=10pt]{standalone}
\usetikzlibrary{arrows.meta,shadows,positioning}
\usepackage{enumitem}
\usepackage{courier}
\renewcommand*\familydefault{\ttdefault}
\begin{document}
\begin{tikzpicture}
  [
    node distance=3cm,
    basic/.style={%
      draw, fill=white
    },
    files/.style = {%
      basic,
      text width=3cm,
      minimum height=1.5cm
    },
    function/.style = {%
      basic,
      text width=3cm,
      minimum height=1.5cm,
      text centered
    },
    box/.style = {%
      basic,
      minimum width=2cm,
      minimum height=0.5cm
    },
    arrow/.style={%
      ->, >=Latex,
    },
  ]
  \begin{scope}[local bounding box=output]
    \draw (0,0) -- (0,1) node[above, box, drop shadow] {Struct};
    \draw (-1.5,-1) -- (-1.5,0) -- (1.5,0) -- (1.5,-1);
    \draw (-0.5,-1) -- (-0.5,0);
    \draw (0.5,-1) -- (0.5,0);
  \end{scope}
  \node (function) [function, left= of output, drop shadow] {Function};
  \node (files) [files, drop shadow, left=of function,] {%
    \vspace*{-.5\baselineskip}%
    \begin{itemize}[nosep,leftmargin=*]
      \item{file1.dat}
      \item{file2.dat}
      \item{file3.dat}
      \item{file4.dat}
    \end{itemize}
  };
  \draw [arrow] (files) -- (function);
\end{tikzpicture}
\end{document}

Another option is to use a pic however the pic stuff is buggy and the bugs do not show any sign of being fixed soon. While pics still work well in many cases, I think the bugginess would be a particular disadvantage here as it affects both relative positioning and naming. If these bugs are fixed at some happy future date, this would probably be the best option, however, as it would be more flexible than using a named scope.

Finally, the fit library could be used to put a node around nodes and coordinates in the scope. However, this would have no real advantages over the use of local bounding box above and would be a lot more hassle to implement. (You'd need to place coordinates on the lines for the fitted node as it can't use paths, as opposed to nodes and coordinates, when figuring out its intended contents.)