Running examples in ‘gtools-Ex.R’ failed
The error most likely occurred in:

> ### Name: keywords
> ### Title: List valid keywords for R man pages
> ### Aliases: keywords
> ### Keywords: documentation
> 
> ### ** Examples
> 
> ## Show all valid R keywords
> keywords()
GROUPED Keywords
----------------

Graphics
	aplot		&	Add to Existing Plot / internal plot
	dplot		&	Computations Related to Plotting
	hplot		&	High-Level Plots
	iplot		&	Interacting with Plots
	color		&	Color, Palettes etc
	dynamic		&	Dynamic Graphics
	device		&	Graphical Devices

Basics
	sysdata		&	Basic System Variables		[!= S]
	datasets	&	Datasets available by data(.)	[!= S]
	data		&	Environments, Scoping, Packages [~= S]
	manip		&	Data Manipulation
	attribute	&	Data Attributes
	classes		&	Data Types (not OO)
	    & character	&	Character Data ("String") Operations
	    & complex	&	Complex Numbers
	    & category	&	Categorical Data
	    & NA	&	Missing Values			[!= S]
	list		&	Lists
	chron		&	Dates and Times
	package		&	Package Summaries

Mathematics
	array		&	Matrices and Arrays
	      & algebra &	Linear Algebra
	arith		&	Basic Arithmetic and Sorting	[!= S]
	math		&	Mathematical Calculus etc.	[!= S]
	logic		&	Logical Operators
	optimize	&	Optimization
	symbolmath	&	"Symbolic Math", as polynomials, fractions
	graphs		&	Graphs, (not graphics), e.g. dendrograms

Programming, Input/Ouput, and Miscellaneous

	programming	&	Programming
	     & interface&	Interfaces to Other Languages
	IO		&	Input/output
	     & file	&	Files
	     & connection&	Connections
	     & database	&	Interfaces to databases
	iteration	&	Looping and Iteration
	methods		&	Methods and Generic Functions
	print		&	Printing
	error		&	Error Handling

	environment	&	Session Environment
	internal	&	Internal Objects (not part of API)
	utilities	&	Utilities
	misc		&	Miscellaneous
	documentation	&	Documentation
	debugging	&	Debugging Tools

Statistics

	datagen		&	Functions for generating data sets
	distribution	&	Probability Distributions and Random Numbers
	univar		&	simple univariate statistics  [!= S]
	htest		&	Statistical Inference
	models		&	Statistical Models
	    & regression&	Regression
	    & &nonlinear&	Non-linear Regression (only?)
	robust		&	Robust/Resistant Techniques
	design		&	Designed Experiments
	multivariate	&	Multivariate Techniques
	ts		&	Time Series
	survival	&	Survival Analysis
	nonparametric	&	Nonparametric Statistics [w/o 'smooth']
	smooth		&	Curve (and Surface) Smoothing
	     & loess	&	Loess Objects
	cluster		&	Clustering
	tree		&	Regression and Classification Trees
	survey		&	Complex survey samples


MASS (2, 1997)
--------------

add the following keywords :

	classif		&	Classification	['class' package]
	spatial		&	Spatial Statistics ['spatial' package]
	neural		&	Neural Networks ['nnet'	 package]

> 
> ## Show keywords associated with the 'merge' function
> keywords(merge)

Execution halted