infix: Resolve a variable to a default when NULL

In tractor.base: Read, Manipulate and Visualise Magnetic Resonance Images

Resolve a variable to a default when NULL

Description

This is a very simple infix function for the common TractoR idiom whereby NULL is used as a default argument value, but later needs to be resolved to a meaningful value if not overridden in the call. It returns its first argument unless it is NULL, in which case it falls back on the second argument.

Usage

X %||% Y

Arguments

X, Y	R objects, possibly NULL.

Value

X, if it is not NULL; otherwise Y.

Author(s)

Jon Clayden

References

Please cite the following reference when using TractoR in your work:

J.D. Clayden, S. Muñoz Maniega, A.J. Storkey, M.D. King, M.E. Bastin & C.A. Clark (2011). TractoR: Magnetic resonance imaging and tractography with R. Journal of Statistical Software 44(8):1-18. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.18637/jss.v044.i08")}.

See Also

where, which resolves a value if an expression is TRUE. Several calls to that function can be conveniently chained together with this one.

tractor.base documentation built on May 29, 2024, 7:58 a.m.