lorentz (version 1.1-3)

Extract.3vel: Extract or replace parts of three-velocity

Description

Extract or replace subsets of three-velocities

Usage

# S3 method for vec
[(x, i, j, drop=TRUE, ...)
# S3 method for 3vel
[(x, i, j) <-  value
# S3 method for 4vel
[(x, i, j) <-  value

Arguments

x

A three-vector

i,j

elements to extract or replace

value

replacement value

drop

Boolean, with default TRUE meaning to drop values

...

Further arguments, currently ignored

Details

These methods (should) work as expected: an object of class 3vel is a three-column matrix with rows corresponding to three-velocities; a single argument is interpreted as a row number. Salient use-cases are u[1:5] <- u[1] and u[1] <- 0.

To extract a single component, pass a second index: u[,1] returns the x- component of the three-velocity.

Extraction functions take a drop argument, except for x[i] which returns a vec object.

Currently, u[] returns u but I am not sure this is desirable. Maybe it should return unclass(u) or perhaps c(unclass(u)).

Use idiom u[] <- x to replace entries of u elementwise.

Examples

u <- r3vel(10)
u[1:4]
u[5:6] <- 0

u[7:8] <- u[1]

u[,1] <- 0.1