Bottom arrow between cells in latex

Question

How can I draw bottom arrows from cell to cell at the borders of a table? More precisely I'd like to get something like this:

\begin{tikzpicture}[
%  -{Stealth[length = 2.5pt]},
start chain = going right,
node distance = 0pt,
MyStyle/.style={draw, minimum width=1.6em, minimum height=2em, outer sep=0pt, on chain}, ]
\node [MyStyle] (1) {$A$};
\node [MyStyle] (2) {$B$};
\node [MyStyle] (3) {$C$};
\node [MyStyle] (4) {$D$};
\node [MyStyle] (5) {$E$};
\node [MyStyle] (6) {$F$};
\node [MyStyle] (7) {$G$};
\node [MyStyle] (8) {$Q$};
\node [MyStyle] (9) {$B$};
\node [MyStyle] (10) {$G$};
\node [MyStyle] (11) {$A$};
\node [MyStyle] (12) {$D$};
\node [MyStyle] (13) {$W$};
\node [MyStyle] (14) {$B$};
\node [MyStyle] (15) {$n$};
\node [MyStyle] (16) {$6$};
\begin{scope}%[-{Stealth[length = 2.5pt]}]
%\draw (1.north) [out=25, in=155] to (2.north);
%\draw (1.north) [out=30, in=155] to (3.north);
\draw (1.north) [out=35, in=155] to (4.north);
\draw (1.north) [out=40, in=155, below] to (6.north);
\draw (1.south) [out=40, in=155, below] to (6.south);
\end{scope}
%\draw[decorate,decoration={brace, amplitude=10pt, raise=5pt, mirror}]
%(2.south west) to node[black,midway,below= 15pt] {$k$-elements} (7.south east);%
\end{tikzpicture}

This code produces the following output:

Problem: Bottom arrows between items.

Code is based on: proportional boxes in Tikz (array diagram)

Answer 1

For the arcs below the scheme, you need negative in and out angles. However, this answer is also to propose an arguably simpler way to draw the scheme as a matrix. The third example has the baselines aligned.

\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{chains,%<- for the first picture
matrix}%<- for the second picture
\begin{document}
\begin{tikzpicture}[
start chain = going right,
node distance = 0pt,
MyStyle/.style={draw, minimum width=1.6em, minimum height=2em, outer sep=0pt, on chain}, ]
\node [MyStyle] (1) {$A$};
\node [MyStyle] (2) {$B$};
\node [MyStyle] (3) {$C$};
\node [MyStyle] (4) {$D$};
\node [MyStyle] (5) {$E$};
\node [MyStyle] (6) {$F$};
\node [MyStyle] (7) {$G$};
\node [MyStyle] (8) {$Q$};
\node [MyStyle] (9) {$B$};
\node [MyStyle] (10) {$G$};
\node [MyStyle] (11) {$A$};
\node [MyStyle] (12) {$D$};
\node [MyStyle] (13) {$W$};
\node [MyStyle] (14) {$B$};
\node [MyStyle] (15) {$n$};
\node [MyStyle] (16) {$6$};
\begin{scope}%[-{Stealth[length = 2.5pt]}]
%\draw (1.north) [out=25, in=155] to (2.north);
%\draw (1.north) [out=30, in=155] to (3.north);
\draw (1.north) [out=35, in=155] to (4.north);
\draw (1.north) [out=40, in=155] to (6.north);
\draw (1.south) [out=-40, in=-155] to (6.south);
\end{scope}
%\draw[decorate,decoration={brace, amplitude=10pt, raise=5pt, mirror}]
%(2.south west) to node[black,midway,below= 15pt] {$k$-elements} (7.south east);%
\end{tikzpicture}

\begin{tikzpicture}
\matrix[matrix of math nodes,column sep=-\pgflinewidth/2,
cells={nodes={draw, minimum width=1.6em, minimum height=2em,anchor=center,
alias=\the\pgfmatrixcurrentcolumn}}]
 (mat){
A & B & C & D & E & F & G & Q & B & G & A & D & W & B & n & 6 \\ };
\draw (1.north) [out=35, in=155] to (4.north);
\draw (1.north) [out=40, in=155] to (6.north);
\draw (1.south) [out=-40, in=-155] to (6.south);
\end{tikzpicture}

\begin{tikzpicture}
\matrix[matrix of math nodes,column sep=-\pgflinewidth/2,
cells={nodes={draw, minimum width=1.6em, text height=1.2em,text depth=0.3em,anchor=center,
alias=\the\pgfmatrixcurrentcolumn}}]
 (mat){
A & B & C & D & E & F & G & Q & B & G & A & D & W & B & n & 6 \\ };
\draw (1.north) [out=35, in=155] to (4.north);
\draw (1.north) [out=40, in=155] to (6.north);
\draw (1.south) [out=-40, in=-155] to (6.south);
\end{tikzpicture}
\end{document}

You may also want to make the arrows distinguishable. One option is to shift the point where the arrow attaches depending on the horizontal distance between start and target. This can be achieved with the show path construction decoration.

\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{matrix,arrows.meta,bending,calc,decorations.pathreplacing}%
\begin{document}
\tikzset{distinguishable arrows/.style={%
decoration={show path construction,
curveto code={
\draw[#1] let \p1=($(\tikzinputsegmentlast)-(\tikzinputsegmentfirst)$) in 
([xshift=-\x1/40]\tikzinputsegmentfirst) .. controls
(\tikzinputsegmentsupporta) and (\tikzinputsegmentsupportb)
..([xshift=\x1/40]\tikzinputsegmentlast);
},
}}}
\begin{tikzpicture}[connect/.style=]
 \matrix[matrix of math nodes,column sep=-\pgflinewidth/2,
 cells={nodes={draw, minimum width=1.6em, 
 text height={height("A")+0.3em},text depth=0.3em,anchor=center,
 alias=\the\pgfmatrixcurrentcolumn}}]
  (mat){
    A & B & C & D & E & F & G & Q & B & G & A & D & W & B & n & 6 \\ };
\begin{scope}[distinguishable arrows={-{Stealth[bend]}}]
 \draw[decorate] (1.north) to[out=40, in=140]  (2.north);
 \draw[decorate] (1.north) to[out=50, in=130]  (3.north);
 \draw[decorate] (1.north) to[out=60, in=120]  (4.north);
 \draw[decorate] (1.north) to[out=70, in=110]  (6.north);
 \draw[decorate] (1.south) to[out=-70, in=-110]  (6.south);
\end{scope}
\end{tikzpicture}
\end{document}

One can also implement other prescriptions.

Answer 2

I would use bend left=<angle> for arrows above nodes chain and bend right=<angle> for arrows below of nodes' chain:

\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{chains}

\begin{document}
\begin{tikzpicture}[
  start chain = A going right,
node distance = 0pt,
   bend angle = 45,
   box/.style = {draw, minimum width=1.6em, minimum height=2em, outer sep=0pt, on chain=A} 
                    ]
\foreach \i in {A,B,C,D,E,F,G,Q,B,G,A,D,W,B,n,6}
    \node[box] {\i};
%    
\draw   (A-1.north) to [bend  left] (A-4.north) 
        (A-1.north) to [bend  left] (A-6.north)
        (A-1.south) to [bend right] (A-6.south);
\end{tikzpicture}
\end{document}

Answer 3

I wrote a command \fromto that automates the arrow plotting calculations for your chain.

This command is directional. That is to say, if you draw an arrow from left to right, it is placed above the chain (in the example below in blue), if you build it from right to left, it is placed below (in the example below in red).

This command is derived from my answer here where you will find explanations of how it works (it uses the properties of the plan rotations).

The first parameter is optional and allows you to transmit the Tikz options to the command.

\newcommand{\fromto}[3][]{% new command \fromto
    \path[draw,thick,#1]($(#2.center)!4mm!90:(#3.center)$)..controls ($(#2.center)!12mm!90:(#3.center)$)  and ($(#3.center)!12mm!-90:(#2.center)$).. ($(#3.center)!4mm!-90:(#2.center)$);}

\documentclass[border=5mm,tikz]{standalone}
\usepackage{tikz}
\usetikzlibrary{chains,arrows.meta}
\usetikzlibrary{calc} %<- calc library


\newcommand{\fromto}[3][]{% new command \fromto
    \path[draw,thick,#1,->]($(#2.center)!4mm!90:(#3.center)$)..controls ($(#2.center)!12mm!90:(#3.center)$)  and ($(#3.center)!12mm!-90:(#2.center)$).. ($(#3.center)!4mm!-90:(#2.center)$);}
\begin{document}

\begin{tikzpicture}[
%  -{Stealth[length = 2.5pt]},
start chain = going right,
node distance = 0pt,
MyStyle/.style={draw, minimum width=1.6em, minimum height=2em, outer sep=0pt, on chain}, ]
\node [MyStyle] (1) {$A$};
\node [MyStyle] (2) {$B$};
\node [MyStyle] (3) {$C$};
\node [MyStyle] (4) {$D$};
\node [MyStyle] (5) {$E$};
\node [MyStyle] (6) {$F$};
\node [MyStyle] (7) {$G$};
\node [MyStyle] (8) {$Q$};
\node [MyStyle] (9) {$B$};
\node [MyStyle] (10) {$G$};
\node [MyStyle] (11) {$A$};
\node [MyStyle] (12) {$D$};
\node [MyStyle] (13) {$W$};
\node [MyStyle] (14) {$B$};
\node [MyStyle] (15) {$n$};
\node [MyStyle] (16) {$6$};
\begin{scope}[-{Stealth[length = 2.5pt]}]
\fromto{1}{2}
\fromto{1}{5}
\fromto{1}{14}
\fromto{6}{1}
\fromto{8}{3}
\end{scope}

\end{tikzpicture}

\end{document}