TikZ, PGFPlots, and Technical Graphics

TikZ creates diagrams, flowcharts, and geometry; PGFPlots builds on TikZ for axes and data plots. Both produce scalable vector graphics that can match document fonts and notation.

EasyLaTeX compiler setting: pdfLaTeX with article. Load tikz for diagrams or pgfplots for plots. Complex figures increase compilation time.

When to Draw with Code#

Code-based drawing offers reproducibility, version control, and consistent fonts. Choose a specialist tool when that better suits the figure, then import a stable output format.

A Minimal TikZ Diagram#

Load TikZ in the preamble:

\usepackage{tikz}

Draw axes and a line segment:

\begin{tikzpicture}
  \draw[->] (0,0) -- (4,0) node[right] {$x$};
  \draw[->] (0,0) -- (0,3) node[above] {$y$};
  \draw[blue,thick] (0,0) -- (3,2);
\end{tikzpicture}

With ordinary Cartesian coordinates, the default axes use 1 cm units. \draw creates paths, square brackets set styles, and node adds text.

Nodes and Arrows#

Define styles and reuse them:

\begin{tikzpicture}[
  box/.style={draw, rounded corners, minimum width=2.5cm, minimum height=8mm},
  arrow/.style={->, thick}
]
  \node[box] (input) {Input data};
  \node[box, right=1.5cm of input] (process) {Process};
  \node[box, right=1.5cm of process] (output) {Output};
  \draw[arrow] (input) -- (process);
  \draw[arrow] (process) -- (output);
\end{tikzpicture}

The right=... of ... syntax needs the positioning library:

\usetikzlibrary{positioning}

Shared styles keep diagrams consistent. Shorten long labels or set text width rather than letting nodes overlap.

A Minimal PGFPlots Plot#

Load PGFPlots and set the compatibility level:

\usepackage{pgfplots}
\pgfplotsset{compat=1.18}

Plot inline coordinates:

\begin{tikzpicture}
  \begin{axis}[
    xlabel={Time (s)},
    ylabel={Velocity (m/s)},
    grid=major
  ]
    \addplot coordinates {(0,0) (1,1) (2,4) (3,9)};
  \end{axis}
\end{tikzpicture}

axis manages axes, ticks, labels, and grids; \addplot supplies a series. Name quantities and units clearly, and do not distinguish series by color alone.

Read Data from a File#

Create data/velocity.csv in the project:

time,velocity
0,0
1,1
2,4
3,9

Then read the named columns:

\addplot table [x=time, y=velocity, col sep=comma] {data/velocity.csv};

Separating data from drawing code makes updates and checking easier. Column names must match the x= and y= selections.

Put the Graphic in the Document#

Wrap the drawing in figure for a caption, label, and reference:

\begin{figure}[tbp]
  \centering
  % tikzpicture or axis goes here
  \caption{Velocity over time}
  \label{fig:velocity}
\end{figure}

Use the caption to explain the content, data source, and uncertainty where relevant. The drawing code is not a substitute for that explanation.

Common Problems#

Environment tikzpicture undefined#

Load tikz; node positioning also needs \usetikzlibrary{positioning}.

Environment axis undefined#

Load pgfplots, not just TikZ. The axis environment belongs to PGFPlots.

Slow Compilation#

Reduce unnecessary samples and layers and use prepared data files. For a very large drawing, use a separate drawing project, compile and download its PDF, then upload that PDF as an image in the main project.

Complete Example#

\documentclass[a4paper,12pt]{article}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}

\begin{document}

\begin{figure}[tbp]
  \centering
  \begin{tikzpicture}
    \begin{axis}[
      width=0.75\linewidth,
      xlabel={Time (s)},
      ylabel={Velocity (m/s)},
      grid=major
    ]
      \addplot[blue,thick,mark=*] coordinates {
        (0,0) (1,1) (2,4) (3,9)
      };
    \end{axis}
  \end{tikzpicture}
  \caption{Velocity over time}
  \label{fig:velocity}
\end{figure}

\end{document}