LaTeX Figures and Tables

Figures and tables are the backbone of a paper. This article covers four things: figure insertion commands and floats, basic tables, the academic-standard three-line table, and merging cells.

LaTeX's management philosophy for figures and tables is consistent with its numbering: you only need to provide the content and title; position, numbering, and references are all automatic.

Inserting Images: graphicx Package

Inserting figures requires only two commands: load graphicx in the preamble, and use \includegraphics in the body to place the image file.

Filename RecommendationsOmitting the extension: write sin rather than sin.png. LaTeX will automatically search for a format supported by the current compiler (XeLaTeX supports PDF, PNG, JPG, etc.), so you don't need to change the source when switching formats.

When controlling image size, prefer a proportional value like width=\textwidth over scale—the former guarantees the image never exceeds the text width, while the latter may unexpectedly overflow under different font-size settings.

Floats: figure Environment

Images should not sit directly in the text flow; the standard practice is to place them in a figure float environment.

The brackets after the environment name are "placement suggestions," telling LaTeX where you'd like it to appear.

"Why did my figure move somewhere else?"—This is not a bug; it's the float mechanism at work: LaTeX chooses a position for each figure that doesn't create large gaps. If you really need to pin it down, use the [H] parameter from the float package (capital H, meaning "here" and don't move it).

Basic Tables: tabular Environment

The syntax skeleton of a table is the same as a matrix: & separates columns, \\ starts a new row, and the column format is declared in the environment parameters.

Academic Standard: booktabs Three-line Table

Open any professional publication, and the tables have "three horizontal lines and zero vertical lines"—this is called a three-line table, provided by the booktabs package.

Format guidelines for journals and theses almost universally require three-line tables. Using | and \hline to create full-border tables is fine for everyday homework, but be sure to switch to booktabs before submitting—vertical lines in professional typography are a sign of "amateur."

Merging Cells: multirow and multicolumn

Complex headers require merging: use \multicolumn for horizontal merging (built into LaTeX) and \multirow for vertical merging (requires loading the multirow package).

Table Captions and Overall Floats

Tables also live in a float; the environment is table, and everything else works exactly like figure.

Two unwritten conventions: place the table captionabove the table, and the figure captionbelow the figure; use tab: and fig: as label prefixes for tables and figures respectively, so you can tell the type at a glance when referencing.

When a table is wider than the text area, there are two quick fixes: wrap the entire tabular in \resizebox{\textwidth}{!}{...} for proportional scaling; or switch to the tabularx package to automatically distribute column widths. The former is fast, the latter is more proper.

Summary