nearest: Index of a vector nearest in value to a supplied value

In GenKern: Functions for generating and manipulating binned kernel density estimates

Description

Returns the index of a vector which contains the value closest to an arbitary value

Usage

nearest(x, xval, outside=FALSE, na.rm=FALSE)

Arguments

x	vector of values
xval	value to find the nearest value in x to
outside	if not set to TRUE the function returns an error if xval is outside the range of x - default FALSE
na.rm	NA behaviour: TRUE drops cases with NA's, FALSE stops function with a warning if NA's are detected: default=FALSE

Value

returns an integer:

index

the index of x with the value nearest to xval

Acknowledgements

Written in collaboration with A.M.Pollard <[e-mail]> with the financial support of the Natural Environment Research Council (NERC) grant GR3/11395

Note

The vector doesn't have to be in any particular order - this routine will just give the index of the nearest number. The only inconsistancy is that if the value of xval are not strictly within the range of the vector the function will return an error. To prevent this call with the outside=TRUE flag enabled. If there are many values which match the 'nearest' value then the function will return a vector of their indicies.

Author(s)

David Lucy <[e-mail]> http://www.maths.lancs.ac.uk/~lucy/
Robert Aykroyd <[e-mail]>http://www.amsta.leeds.ac.uk/~robert/

Examples

# make up a vector
x <- c(1,2,2,2,2,2,3,4,5,6,7,8,9,10)
# conventional useage - xval within range should return 9
nearest(x, 4.7)
# xval - outside the range of x should return 14
nearest(x, 12.7, outside=TRUE)
# many 'nearest' values in x - should return - 2 3 4 5 6 
nearest(x, 1.7)
# make x[3] an NA
x[3] <- NA
# returns - 2 4 5 6 - by enabling na.rm
nearest(x, 1.7, na.rm=TRUE)

GenKern documentation built on May 2, 2019, 3:25 a.m.