# Simple Gantt Charts in LaTeX

Gantt charts are often required in grant applications and similar project descriptions. Simple ones can be produced using a spreadsheet. Complex ones can be produced using MS Project, or its open source alternative Project Libre (which is installed in TCM).

In LaTeX the two main options are to use the pgfgantt package, which is very fully featured, or just to use the tabular environment for a simple chart. This page has some suggestions on the latter route.

## The Simple Result

And the source. (Scroll to the bottom of the page for an improved result with colour and lines of varying thickness.)

## Commentary

This solution uses the packages xcolor, colortbl and forloop, the latter being a convenience for setting multiple cells at once. It then defines some convenience macros for setting those multiple cells at once.

\usepackage{forloop}
\newcounter{loopcntr}
\newcommand{\rpt}[2][1]{%
\forloop{loopcntr}{0}{\value{loopcntr}<#1}{#2}%
}
\newcommand{\on}[1][1]{
\forloop{loopcntr}{0}{\value{loopcntr}<#1}{&\cellcolor{gray}}
}
\newcommand{\off}[1][1]{
\forloop{loopcntr}{0}{\value{loopcntr}<#1}{&}
}


With this in place, the table is simply defined as

\noindent\begin{tabular}{p{0.17\textwidth}*{20}{|p{0.01\textwidth}}|}


The \noindent reduces the indentation of the table, and then one has one wide column, followed by twenty narrow columns. Other units of measure could have been used, such as 1in rather than 0.17\textwidth. Note that column separation gaps will mean that the table is a lot wider than the sum of the column widths.

The top line of the table is then generated by

\textbf{Gantt chart} & \multicolumn{4}{c|}{Year 1}
& \multicolumn{4}{c|}{Year 2}
& \multicolumn{4}{c|}{Year 3}
& \multicolumn{4}{c|}{Year 4}
& \multicolumn{4}{c|}{Year 5} \\


and for the next line we make use of the rpt macro we have defined to repeat its argument five times

\rpt[5]{& 1 & 2 & 3 & 4} \\


After this, individual entries are quite straight-forward, with lines such as

PhD 1     \on[16] \off[4]\\
\hline

and
Squashing Bugs \off[2] \on[4] \off[4] \on[1] \off[9] \\
\hline


The only remaining trick is removing the column separators from the work packages line, whilst keeping the vertical line at the right-hand side. This was done with

\textbf{Work \mbox{packages}} & \multicolumn{20}{c|}{} \\


## Possible improvements

### Colours

The colour can readily be changed, either for all cells by changing the "gray" in the definition of the on macro, or for some cells by defining a second on macro, called something like onx (remember digits cannot be a part of macro names), with a different colour specification. Colours guaranteed to exist are black, blue, brown, cyan, darkgray, gray, green, lightgray, lime, magenta, olive, orange, pink, purple, red, teal, violet, white and yellow, and one can add others in the usual way (the following three lines are equivalent):

\definecolor{orange}{rgb}{1,0.5,0}
\definecolor{orange}{RGB}{255,127,0}
\definecolor{orange}{HTML}{FF7F00}


### Thicker vertical lines dividing years

Unfortunately our rpt macro does not work in the columns specification of tabular, so one is left writing something like

\noindent\begin{tabular}{p{0.17\textwidth}
!{\vrule width 0.4mm}p{0.01\textwidth}*{3}{|p{0.01\textwidth}}
!{\vrule width 0.4mm}p{0.01\textwidth}*{3}{|p{0.01\textwidth}}
!{\vrule width 0.4mm}p{0.01\textwidth}*{3}{|p{0.01\textwidth}}
!{\vrule width 0.4mm}p{0.01\textwidth}*{3}{|p{0.01\textwidth}}
!{\vrule width 0.4mm}p{0.01\textwidth}*{3}{|p{0.01\textwidth}}
|}
% The top line
\textbf{Gantt chart} & \multicolumn{4}{c!{\vrule width 0.4mm}}{Year 1}
& \multicolumn{4}{c!{\vrule width 0.4mm}}{Year 2}
& \multicolumn{4}{c!{\vrule width 0.4mm}}{Year 3}
& \multicolumn{4}{c!{\vrule width 0.4mm}}{Year 4}
& \multicolumn{4}{c|}{Year 5} \\


Thank goodness for copy and paste! The rest of the table is unchanged.

And the source.