example of a flow diagram with latex tikzpicture

example_flowdiagram.tex

\documentclass{article}
\usepackage{tikz}
\usepackage{array}
\usepackage{siunitx}

\usetikzlibrary{shapes.geometric, shapes.misc, arrows, fit, calc}

\newcommand\addvmargin[1]{
  \node[fit=(current bounding box),inner ysep=#1,inner xsep=0]{};
}

\tikzstyle{data} = [rectangle, rounded corners, minimum width=3.5cm, minimum height=1cm,text centered, draw=black]
\tikzstyle{filter} = [rectangle, minimum width=2cm, minimum height=1cm, text centered, text width=2cm, draw=black]
\tikzstyle{dataset} = [chamfered rectangle, chamfered rectangle xsep=4cm, draw=black, text centered]
\tikzstyle{decision} = [diamond, draw=black, text centered, minimum width=1.5cm]
  

\tikzstyle{arrow} = [thick,->,>=stealth]

\begin{document}

\centering
\begin{tikzpicture}[node distance=2cm, auto]

% NODES cylinder
\node (data1) [data, align=center] {Wang et al 2011 \\ \SI{403} sites \\ \SI{170} proteins};
\node (data2) [data, right of=data1, xshift=2cm, align=center] {Jochmann et al 2014 \\ \SI{1181} sites \\ \SI{540} proteins};

\coordinate (Middle) at ($(data1)!0.5!(data2)$);
\node (filter) [filter, below of=Middle] {Filter redundant sites};

\node (decision1) [decision, below left of=filter, xshift=-.5cm, yshift=-.5cm] {in Sifts};
\node (mss) [dataset, right of=decision1, xshift=1.5cm, align=center] {MSS\\ \SI{1422} sites \\ \SI{640} proteins}; 
\node (uss) [dataset, right of=mss, align=center, xshift=1.5cm]  {USS\\ \SI{98388} sites \\ \SI{640} proteins }; 
\node (gs) [dataset, below of=uss, align=center]  {GS\\ \SI{1164} sites \\ \SI{1164} proteins }; 

\node (decision2) [decision, below left of=decision1, xshift=-2.5cm] {in Blast};
% \node (discard) [filter, left of=decision2, xshift=-1cm] {Discard};

\coordinate (Middle2) at ($(decision1)!0.5!(decision2)$);
\node (ss143) [dataset, below of=Middle2, align=center, xshift=0cm] {ss143 \\ \SI{143} sites \\ \SI{106} proteins}; 

\node (decision3) [decision, below of=ss143, align=center,  yshift=-.5cm] {Complete \\ backbone};
\node (ss131) [dataset, below of=decision3, align=center,  yshift=-.5cm] {SS131\\ \SI{131} sites \\ \SI{0} proteins};  

\draw [arrow] (data1) -| (filter);
\draw [arrow] (data2) -| (filter);
\draw [arrow] (filter) -| (mss);
\draw [arrow] (filter) -| (uss);
\draw [arrow] (filter) -| (decision1);
\draw [arrow] (decision1.south) |- node {yes} (ss143.east) ; 
\draw [arrow] (decision1)  -| node[anchor=south] {no} (decision2) ;
\draw [arrow] (decision2.south) |- node[anchor=north] {yes} (ss143.west) ;
% \draw [arrow] (decision2) -- node[anchor=south] {no} (discard) ;
\draw [arrow] (ss143) -- (decision3) ;
\draw [arrow] (decision3) -- node {yes} (ss131) ;
% \draw [arrow] (decision3) -| node {no} (discard) ;


\node (legend) at (6.5, -10.9){
                   
      \begin{tabular}{| m{.15 \textwidth} |  m{.15 \textwidth} |}
      \hline
      \emph{Legend} & \emph{Symbol} \\      	
      \hline
      
      Data                 & 
      \begin{tikzpicture}[baseline=0]
      \draw[rounded corners] rectangle (1 , 0.45) ;
      \addvmargin{1mm}
      \end{tikzpicture}     \\ \hline

            
      Process                 & 
      \begin{tikzpicture}[baseline=0]
      \draw  rectangle (1 ,0.45) ;
      \addvmargin{1mm}
      \end{tikzpicture}     \\ \hline

       Dataset                 & 
      \begin{tikzpicture}[baseline=0]
      \node  [dataset] { \hspace{1cm}  } ;
      \addvmargin{1mm}
      \end{tikzpicture}     \\ \hline

             Decision                 & 
      \begin{tikzpicture}[baseline=0]
      \node  [decision] {} ;
      \addvmargin{1mm}
      \end{tikzpicture}     \\ \hline

      \end{tabular}
  };
\end{tikzpicture}

\end{document}