TikZ-PGF – How to Draw Complex Pictures with TikZ

tikz-pgftkz-euclide

I am trying to draw this picture

I tried with pgfplots.

\documentclass[border=1.5mm,12pt]{standalone}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
axis line style = very thick,
axis lines = center,
xlabel=$x$, ylabel=$y$,
xtick           = {-1,0,...,4},
ytick           = {-1,0,...,4},
xmin       = -0.5,   xmax = 5.5,
ymin       =-0.5,     ymax = 4.5,
]      
\node at (axis cs:-0.25, -0.25) {$A$};
\node at (axis cs: 4.25, 0.25) {$B$};
\node at (axis cs: 4, 3.25) {$C$};
\node at (axis cs: 0.15, 3.25) {$D$};
\node at (axis cs: 0.2, 1.2) {$M$};
\node at (axis cs: 3, 3.25) {$K$};
\addplot[very thick,mark=*] coordinates {
    (4 ,0) (4,3) (0,3) (0,0)  (0,1)
};
\addplot[mark=*,very thick] coordinates {
    (0,0)  (3,3)};
\addplot[very thick,mark=*] coordinates {
    (4,0)  (0,1)};     
\end{axis}
\end{tikzpicture}
\end{document}

How to draw it with TikZ?

Best Answer

If you place first all the coordinates, the rest is pretty straightforward.

Something like this:

\documentclass[border=2mm,tikz]{standalone}

\begin{document}
\begin{tikzpicture}
  % coordinates
  \coordinate (A) at (0,0);
  \coordinate (B) at (4,0);
  \coordinate (C) at (4,3);
  \coordinate (D) at (0,3);
  \coordinate (K) at (3,3);
  \coordinate (M) at (0,1);
  % axes
  \draw[-latex] (-0.5,0) --++ (5.4,0) node [above] {$x$};
  \draw[-latex] (0,-0.5) --++ (0,5.4) node [right] {$y$};
  \foreach\i in {1,...,4}
  {
    \draw (\i,-0.1) --++ (0,0.2) node [yshift=-4mm] {$\i$};
    \draw (-0.1,\i) --++ (0.2,0) node [xshift=-4mm] {$\i$};
  }
  % lines
  \draw[thick] (A) rectangle (C);
  \draw[thick] (A) -- (K);
  \draw[thick] (B) -- (M);
  % points
  \fill (A) circle (1.5pt) node [below left] {$A$};
  \foreach\i in {B,C,D,K,M}
    \fill (\i) circle (1.5pt) node [above right] {$\i$};
\end{tikzpicture}
\end{document}

Related Solutions

[Tex/LaTex] How to draw this picture with LaTeX? TikZ

I would go the following way:

Define the coordinates for the three dots (for example (0,0), (1.5,1), and (4,2)).
For each coordinate, draw a small filled circle, and put a node below it, with the math formula.
Put the final formula above the last coordinate.
Draw the curve. This is the most difficult part, because connecting coordinates with curved paths require to specify either control points (if drawn as bezier curves), or the incoming and outcoming angle of the curve at each intermediate coordinate. I would go for the second solution.

So, the code could be

\documentclass{article}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
\coordinate (A) at (0,0);
\coordinate (B) at (1.5,1);
\coordinate (C) at (4,2);

\foreach \coor/\formula in {A/{x=\phi(0;x)},B/{y=\phi(t;x)},C/{\phi(s;x)}} {
  \fill (\coor) circle (2pt);
  \node[below right, inner xsep=-1ex] at (\coor) {$\formula$};
}
\node[above] at (C) {$\phi(t+s;x)$};
\draw (A) to[in=190] (B) to[out=10, in=220] (C);
\end{tikzpicture}
\end{document}

Note that the angles at (B) should be carefully choosen so that the curve is smooth at that point. The curve enters (B) at 190 degrees, and leaves it at 10 degrees, so that both directions are colinear.

Result

[Tex/LaTex] Line up nested tikz enviroments or how to get rid of them

As is explained in How do I draw shapes inside a tikz node? pics can be used for defining new objects. My main problem using pics is how to place where you want because they aren't nodes and positioning them is not so easy.

Following code shows how to define EDFA block.

    EDFA/.pic={
        \begin{scope}[scale=.5]
        \draw (-1,0) coordinate (in) --  (-1,1) -- (1,0) coordinate (out) --  (-1,-1) -- cycle;
        \node[anchor=north,inner sep=2pt] at (0,-1) {$1$};
        \end{scope}

In this case, coordinate (-1,0) will act as west anchor and 1,0 as east. Both point will have an special name for further reference. Every pic is placed according its own origin (0,0). You can use Claudio's answer to Anchoring TiKZ pics for better positioning.

As your example was simple, I'd prefer to star with EDFA and place Source and Sink after it.

\documentclass[]{article}

% tikz
\usepackage{tikz}
\usetikzlibrary{positioning} %relative positioning

\begin{document}

\tikzset{%
    EDFA/.pic={
        \begin{scope}[scale=.5]
        \draw (-1,0) coordinate (in) --  (-1,1) -- (1,0) coordinate (out) --  (-1,-1) -- cycle;
        \node[anchor=north,inner sep=2pt] at (0,-1) {$1$};
        \end{scope}
    }
}

\begin{tikzpicture}[
block/.style={draw},
]

\draw pic (edfa) {EDFA};

\node[block, left=of edfain] (source) {Source};

\node[block, right= of edfaout] (sink) {Sink};

\draw[->] (source) -- (edfain);
\draw[->] (edfaout) -- (sink);

\end{tikzpicture}

\end{document}

I understand that your components are more complex than EDFA because for this particular case an isosceles triangle node with a label will do the work and it can be used as a node and not as a pic:

\documentclass[]{article}

% tikz
\usepackage{tikz}
\usetikzlibrary{positioning} %relative positioning
\usetikzlibrary{shapes.geometric}

\begin{document}

\begin{tikzpicture}[
    block/.style={draw},
    edfa/.style={isosceles triangle, minimum width=1cm, 
         draw, anchor=west, isosceles triangle stretches, 
         minimum height=1cm, label=-80:#1}
]

\node[block] (source) {Source};

\node[edfa=1, right=of source] (edfa) {};

\node[block, right= of edfa] (sink) {Sink};

\draw[->] (source) -- (edfa);
\draw[->] (edfa) -- (sink);

\end{tikzpicture}

\end{document}

Best Answer

Related Solutions

[Tex/LaTex] How to draw this picture with LaTeX? TikZ

[Tex/LaTex] Line up nested tikz enviroments or how to get rid of them

Related Question