vignettes/object_orientation.Rmd
object_orientation.RmdThe S7 scheme is
used for objects created by functions in the mooring
package.
The functions mooring(), segmentize() and
knockdown() all deal with moorings, and they return an
object that is named so that other functions will know how to deal with
the information. Moorings consist of what are called “elements” in the
package, and these are created with a suite of specialized functions. In
common work, the main element-creating functions are
anchor() for creating anchors, wire() for
creating wires, instrument() for creating instruments, and
float() for creating floats. Consult the “see also” section
of the documentation for any of these functions, to discover other
element-creating functions.
Some examples may clarify. First, we create an anchor element, and find its contents.
## Loading required package: S7
a <- anchor()To see it’s contents, simply type its name in an interactive console:
a## <mooring::anchorS7>
## @ model : chr "1 Railway Wheel"
## @ buoyancy : num -350
## @ height : num 0.15
## @ area : num 0
## @ CD : num 1.3
## @ source : chr "Dewey"
## @ originalName: chr "1 Railway Wheel"
## @ x : num 0
## @ x0 : num 0
## @ z : num 0
## @ z0 : num 0
## @ phi : num 0
## @ tau : num 0
## @ group : num 0The individual components can be accessed with the @
syntax used by S7.
For example, the buoyancy (the negative of the ‘weight’ in water,
expressed in kg) as
a@buoyancy## [1] -350You may also alter the components easily; e.g. the following reduces the height of this anchor to zero.
a@height <- 0
a## <mooring::anchorS7>
## @ model : chr "1 Railway Wheel"
## @ buoyancy : num -350
## @ height : num 0
## @ area : num 0
## @ CD : num 1.3
## @ source : chr "Dewey"
## @ originalName: chr "1 Railway Wheel"
## @ x : num 0
## @ x0 : num 0
## @ z : num 0
## @ z0 : num 0
## @ phi : num 0
## @ tau : num 0
## @ group : num 0Using e.g. anchor("?") gives a list of built-in anchor
types, and it is not uncommon to construct mooring elements by staring
with a known element and changing some quantities.
Turning to moorings, a 4-element case will suffice for illustration.
As the reader has no doubt guessed, the way to find the contents is to name the object.
m## <mooring::mooringS7>
## @ elements :List of 3
## .. $ : <mooring::floatS7>
## .. ..@ model : chr "Kiel SFS40in"
## .. ..@ buoyancy : num 320
## .. ..@ height : num 1
## .. ..@ area : num 0.785
## .. ..@ CD : num 0.65
## .. ..@ source : chr "Dewey"
## .. ..@ originalName: chr "Kiel SFS40in"
## .. ..@ x : num 0
## .. ..@ x0 : num 0
## .. ..@ z : num -23.8
## .. ..@ z0 : num -23.8
## .. ..@ phi : num 0
## .. ..@ tau : num 320
## .. ..@ group : num 0
## .. $ : <mooring::wireS7>
## .. ..@ model : chr "1/4in wire/jack"
## .. ..@ buoyancy : num -9.75
## .. ..@ height : num 75
## .. ..@ area : num 0.6
## .. ..@ CD : num 1.3
## .. ..@ source : chr "Dewey"
## .. ..@ originalName: chr "1/4 wire/jack"
## .. ..@ x : num 0
## .. ..@ x0 : num 0
## .. ..@ z : num -24.8
## .. ..@ z0 : num -24.8
## .. ..@ phi : num 0
## .. ..@ tau : num 310
## .. ..@ group : num 0
## .. $ : <mooring::anchorS7>
## .. ..@ model : chr "1 Railway Wheel"
## .. ..@ buoyancy : num -350
## .. ..@ height : num 0.15
## .. ..@ area : num 0
## .. ..@ CD : num 1.3
## .. ..@ source : chr "Dewey"
## .. ..@ originalName: chr "1 Railway Wheel"
## .. ..@ x : num 0
## .. ..@ x0 : num 0
## .. ..@ z : num -99.8
## .. ..@ z0 : num -99.8
## .. ..@ phi : num 0
## .. ..@ tau : num 310
## .. ..@ group : num 0
## @ waterDepth: num 100
## @ u : num 0
## @ attributes: list()The way to get the top element is e.g.
m@elements[[1]]## <mooring::floatS7>
## @ model : chr "Kiel SFS40in"
## @ buoyancy : num 320
## @ height : num 1
## @ area : num 0.785
## @ CD : num 0.65
## @ source : chr "Dewey"
## @ originalName: chr "Kiel SFS40in"
## @ x : num 0
## @ x0 : num 0
## @ z : num -23.8
## @ z0 : num -23.8
## @ phi : num 0
## @ tau : num 320
## @ group : num 0