R: free operator language. (自由演算子言語R）

In R, you can freely define a new binary operator with the form of %hoge% where hoge is arbitral literal. This philosophy allows us to flexibly extend the original syntax; actually free operators are sometimes very useful in terms of readability/writability.

At the same time, however, this means R has a lot of duplicated operators as shown below. If you load two or more packages that export free operators, you may suffer from name conflicts and it will be hard to predict the behavior.

（Rって好きに演算子作れて、それはそれでいいんだけど、パッケージ間の名前衝突多すぎて危ないんじゃね？）

Data from http://finzi.psych.upenn.edu/R/library/ on Oct, 25, 2014.

We show only the packages on CRAN, but recent packages on github may tend more to use free operator.

（CRANのパッケージだけ載せてるけど、githubの奴も入れるともっと多いかも）

Duplicated free operators (重複のある自由演算子)

Ind	Op	Package	Description
1	%nin%	BBmisc	Simply a negated 'in' operator.
1	%nin%	DescTools	Find Matching (or Non-Matching) Elements
1	%nin%	Hmisc	Find Matching (or Non-Matching) Elements
1	%nin%	memisc	Negative Match
2	%*%	bigalgebra	%*%,big.matrix,big.matrix-method
2	%*%	compositions	inner product for matrices and vectors
2	%*%	compositions	inner product for datasets with a vector space structure
2	%*%	compositions	inner product for datasets with vector scale
2	%*%	gmatrix	Matrix Multiplication
2	%*%	HiPLARM	Matrix Multiplication of two matrices using GPU or multi-core
2	%*%	kinship	Basic Linear Algebra for classes bdsmatrix and
2	%*%	Matrix	Matrix (Cross) Products (of Transpose)
2	%*%	orientlib	%*%,orientation,orientation-method
2	%*%	quaternions	Linear Algebra with quaternions
3	%>%	dendextend	Pipe an object forward into a function call/expression.
3	%>%	ggvis	Pipe graphics
3	%>%	gmailr	Pipe statements
3	%>%	magrittr	Pipe an object forward into a function call/expression.
4	%+%	DepthProc	Adds plots
4	%+%	Jmisc	Concatenate two strings
4	%+%	lava	Concatenation operator
4	%+%	stringi	Concatenate Two Character Vectors
5	%in%	discreteRV	Generic method for in operator function
5	%in%	flowCore	Filter-specific membership methods
6	%s%	matrixcalc	Direct sum of two arrays
6	%s%	Rgnuplot	String concatenation operator
7	%!in%	operator.tools	Logical Operator: NOT IN
7	%!in%	operators	Not in
8	%~%	operators	Pattern matching operators
8	%~%	reportr	Test a character vector for a match against a regular expression
9	%<%	scidb	Masking comparison methods from package 'scidb'
9	%<%	stringi	Compare Strings with or without Collation
9	%<%	TeachingDemos	Less than or Less than and equal operators that can be chained

A complete list of free operators (全自由演算子の一覧）

Op	Package	Description
%same%	BayesFactor	Compare two objects to see if they are the 'same', for some loose
%termin%	BayesFactor	Find a model term in a vector of
%btwn%	BBmisc	Check if some values are covered by the range of the values in a
%nin%	BBmisc	Simply a negated 'in' operator.
%nin%	DescTools	Find Matching (or Non-Matching) Elements
%nin%	Hmisc	Find Matching (or Non-Matching) Elements
%nin%	memisc	Negative Match
%inInterval%	BEQI2	Test if a Value is in an Interval
%*%	bigalgebra	%*%,big.matrix,big.matrix-method
%*%	compositions	inner product for matrices and vectors
%*%	compositions	inner product for datasets with a vector space structure
%*%	compositions	inner product for datasets with vector scale
%*%	gmatrix	Matrix Multiplication
%*%	HiPLARM	Matrix Multiplication of two matrices using GPU or multi-core
%*%	kinship	Basic Linear Algebra for classes bdsmatrix and
%*%	Matrix	Matrix (Cross) Products (of Transpose)
%*%	orientlib	%*%,orientation,orientation-method
%*%	quaternions	Linear Algebra with quaternions
%>%	dendextend	Pipe an object forward into a function call/expression.
%>%	ggvis	Pipe graphics
%>%	gmailr	Pipe statements
%>%	magrittr	Pipe an object forward into a function call/expression.
%+%	DepthProc	Adds plots
%+%	Jmisc	Concatenate two strings
%+%	lava	Concatenation operator
%+%	stringi	Concatenate Two Character Vectors
%c%	DescTools	Concatenates two strings without any separator.
%like%	DescTools	Like operator
%overlaps%	DescTools	Determines If And How Extensively Two Date Ranges Overlap
%AND%	discreteRV	Compute the logical AND of two events
%in%	discreteRV	Generic method for in operator function
%in%	flowCore	Filter-specific membership methods
%OR%	discreteRV	Compute the logical OR of two events
%dorng%	doRNG	Reproducible Parallel Foreach Backend
%contains%	dostats	Does a table contain a value
%SplitOn%	favir	Split a character type at the given substring
%on%	flowCore	Methods for Function %on% in Package 'flowCore'
%must%	futile.paradigm	Add post-assertion validations to a function to
%when%	futile.paradigm	Add guards to a function to define the
%._.%	labeledLoop	Labeled loop and break
%as%	lambda.r	Define functions and type constructors in lambda.r
%isa%	lambda.r	Functions for duck typing
%ni%	lava	Matching operator (x not in y) oposed to the '%in%'-operator (x in y)
%m+%	lubridate	Add and subtract months to a date without exceeding the last day
%within%	lubridate	Tests whether a date or interval falls within an interval
%s%	matrixcalc	Direct sum of two arrays
%s%	Rgnuplot	String concatenation operator
%!in%	operator.tools	Logical Operator: NOT IN
%!in%	operators	Not in
%-~|%	operators	Remove a pattern from a character vector
%/~%	operators	Divide by a pattern
%+=%	operators	Plus Equal Operators
%<<%	operators	Read or write an R object to/from a file
%|%	operators	Pipe an R object to a unix command
%~%	operators	Pattern matching operators
%~%	reportr	Test a character vector for a match against a regular expression
%~|%	operators	Regular expression filters
%but%	operators	Modification of function arguments
%o~%	operators	Only keeps the macthing part of a regular expression
%of%	operators	Is an object of a given class
%without%	operators	Remove certain elements from a vector
%x=%	operators	Creates string decorators by repeating a pattern
%k%	opm	Query metadata keys
%q%	opm	Query metadata
%grep%	osmar	Binary operators for grep-like functions
%>>%	pipeR	Pipe an object forward
%--%	powerr	Binary operator %-%
%.*%	powerr	Binary operator %.*%
%**%	powerr	Binary operator %**%
%++%	powerr	Binary operator %++%
%<a-%	pryr	Create an active binding.
%<c-%	pryr	Create a constant (locked) binding.
%<d-%	pryr	Create an delayed binding.
%.%	pvar	Concatenate strings
%&%	qdap	qdap Chaining
%l*%	qdapTools	Hash/Dictionary Lookup
%append%	RecordLinkage	Concatenate comparison patterns or
%or%	rex	Or
%out%	rmngb	The Opposite of '%in%'
%^%	rmutil	of a Matrix
%and%	RQDA	Binary operations of some types of RQDA objects
%Q-%	RSpincalc	Quaternion subtraction
%Q.%	RSpincalc	Quaternion dot product
%Q*%	RSpincalc	Quaternion multiplication
%Q/%	RSpincalc	Quaternion division
%Q+%	RSpincalc	Quaternion addition
%<%	scidb	Masking comparison methods from package 'scidb'
%<%	stringi	Compare Strings with or without Collation
%<%	TeachingDemos	Less than or Less than and equal operators that can be chained
%tt%	STAR	Time Transformation Using a gssanova Objet
%included%	timetools	test inclusion of 2 'POSIXcti' objects
%intersect%	timetools	intersects 2 'POSIXcti' objects