How to Place 2 TikZ Plots Side by Side

Question

I'm working on something that involves placing plot sketches side by side. The trouble is, even though I begin the next picture on the same line as the previous one ends, it doesn't look nice:

\begin{tikzpicture}

\draw [->] (0,0) -- (0,2) node [left,pos=1] {$\Delta x$} node [above right] at (0.5,2) {Guy};
\draw [->] (0,0) -- (2.1,0) node [below, pos=0.9] {$\Delta t$};
\draw (0,-1) -- (1,0) -- (2,1);

\end{tikzpicture} \begin{tikzpicture}

\draw [->] (0,0) -- (0,2) node [left,pos=1] {$\Delta x$} node [above right] at (0.5,2) {Car};
\draw [->] (0,0) -- (2.1,0) node [below, pos=0.9] {$\Delta t$};
\draw [domain=0:0.89] plot (\x, {2.5*\x*\x});

\end{tikzpicture}

What is wrong, and how can I fix it?

Answer 1

For the sake of illustration, it will be easiest to make your tikzpicture's appear inlign with some text. Normally, the bottom of a tikzpicture is put on the baseline of the surrounding text. So, if we take your code and add A and B on either side, we get:

This makes sense. The lowest point in the first tikzpicture (i.e., the bottom end of the plotted line) is aligned with the baseline of the text, and the lowest point of the second tikzpicture (i.e., the bottom of the label for the x-axis) is also aligned with the baseliene of the surrounding text.

However, you can change this alignment with the TikZ style baseline, which allows you to specify what point will be put on the baseline of surrounding text. baseline is short for baseline=0pt, which puts the x-axis of the tikzpicture on the baseline of the surrounding text:

As you can see, the x-axis is what is aligned to the baseline of the surrounding text. Here's the code for this. (Again, baseline=0pt is the same as baseline.)

MWE

\documentclass{article}

\usepackage{tikz}

\begin{document}

A \begin{tikzpicture}[baseline=0pt]

\draw [->] (0,0) -- (0,2) node [left,pos=1] {$\Delta x$} node [above right] at (0.5,2) {Guy};
\draw [->] (0,0) -- (2.1,0) node [below, pos=0.9] {$\Delta t$};
\draw (0,-1) -- (1,0) -- (2,1);

\end{tikzpicture} \begin{tikzpicture}[baseline=0pt]

\draw [->] (0,0) -- (0,2) node [left,pos=1] {$\Delta x$} node [above right] at (0.5,2) {Car};
\draw [->] (0,0) -- (2.1,0) node [below, pos=0.9] {$\Delta t$};
\draw [domain=0:0.89] plot (\x, {2.5*\x*\x});

\end{tikzpicture} B

\end{document}

Rather than specifying a particular dimension for baseline, you can also specify a coordinate. For complete details, see page 125 of the current TikZ documentation.