Graphs

You can do vector graphics by using:

\usepackage{tikz}

\begin{tikzpicture}
\end{tikzpicture}

to draw something, we use \draw command (or \filldraw):

\draw[OPTIONS] (START_COORDS) SHAPE (END_COORDS);

The OPTIONS include:

1. color
2. style
3. thickness

Colors

1. white
2. black
3. red
4. green
5. blue
6. cyan
7. magenta
8. yellow

Thickness

1. ultra thin
2. very thin
3. thin
4. thick
5. very thick
6. ultra thick

Nodes

The capitalized words in the following code block are placeholders which I will describe afterwards.

% preamble
\usetikzlibrary{positioning}
% doc starts

\begin{tikzpicture}[
NODE_TYPE/.style={SHAPE, draw=COLOR!INTENSITY, fill=COLOR!INTENSITY, THICKNESS, minimum size=WIDTH},
]
    \node[NODE_TYPE] (NODE_NAME_1)                       {NODE_LABEL};
    \node[NODE_TYPE] (NODE_NAME_2) [below = of NODE_NAME_1]{NODE_LABEL};

    \draw[->] (NODE_NAME.DIRECTION) -- (NODE_NAME.DIRECTION);
\end{tikzpicture}

Let me explain those placeholders now.

• NODE_TYPE is assigned to each node, to identify its type (appearance).
• SHAPE can be circle, rectangle etc.
• DIRECTION can be:
  • east
  • west
  • north
  • south
  • north east
  • north west
  • south east
  • south west
• -- defines a line.
• -> tells the line has to be pointed.

Examples

\draw[red, dashed] (0, 0) rectangle (2, -2) node[anchor=north west, blue] {Hello};

\draw[red, dashed, ultra thick] (0, 0) circle (2);

\begin{tikzpicture}[
roundnode/.style={circle, draw=green!60, fill=green!5, very thick, minimum size=7mm},
squarednode/.style={rectangle, draw=red!60, fill=red!5, very thick, minimum size=5mm},
]
%Nodes
\node[squarednode]      (maintopic)                              {2};
\node[roundnode]        (uppercircle)       [above=of maintopic] {1};
\node[squarednode]      (rightsquare)       [right=of maintopic] {3};
\node[roundnode]        (lowercircle)       [below=of maintopic] {4};

%Lines
\draw[->] (uppercircle.south) -- (maintopic.north);
\draw[->] (maintopic.east) -- (rightsquare.west);
\draw[->] (rightsquare.south) .. controls +(down:7mm) and +(right:7mm) .. (lowercircle.east);
\end{tikzpicture}