downLogs-methods: Methods for "downLogs" Object Construction
In sampSurf: Sampling Surface Simulation for Areal Sampling Methods

Description Methods

The following are the constructor methods for class “downLogs” in Package sampSurf. Please see “The Stem Class” vignette for more information and examples on the usage of the methods.

signature(object = "list", container = "missing")

Ultimately, all of the constructors end up calling this one to generate the object after they have done what they were meant to, and then converted all of the “downLog” objects into a list structure. So if one wishes, one can simply create one's own list of “downLog” objects and use this constructor.

usage...

downLogs(object,
         description = '',
         ... )

object: A list as discussed above.
description: A character description of the collection.
... : Other arguments to be passed along (not used currently).

signature(object = "data.frame", container = "missing")

This particular method allows one to pass a data frame in the form generated from sampleLogs in object argument to construct an object of class “downLogs”. Note, however, that the data frame does not have to be created by sampleLogs, and it does not have to contain synthetic/simulated logs. As long as all of the columns are present that are generated by sampleLogs it will be used; for example, the data frame can be constructed from a field sample of logs.

usage...

downLogs(object, units = 'metric', ... )

object: A data frame as discussed above.
units: The units of measurement.
... : Other arguments to be passed along to the downLog constructor—these apply uniformly to all logs in the collection.

signature(object = "numeric", container = "bufferedTract")

This method will take as its first argument (object) the number of logs to be synthetically generated. The centers of the logs will all lie within the interior region of the “bufferedTract” object passed in the second (container) argument.

usage...

downLogs(object, container, units = 'metric', ... )

object: A numeric (truncated to integer) object specifying the number of logs to generate as discussed above.
container: A “bufferedTract” object specifying the internal portion of the tract within which the log centers will be generated.
units: The units of measurement.
... : Other arguments to be passed along to the last constructor described below.

signature(object = "numeric", container = "missing")

This constructor looks like it just generates logs randomly. But in reality, note the arguments below. It takes limits of a rectangular region as an alternative to specifying a bounding box matrix or a “bufferedTract” object as in two of the other constructors. Essentially, these limits get converted to a matrix bounding box and the appropriate constructor is used (see below).

usage...

downLogs(object,
         xlim = c(0,100), 
         ylim = c(0,50),
         units = 'metric',
         ...)

object: See explanation in the following constructor method.
units: The units of measurement.
xlim: Limits for the bounding rectangle in x.
ylim: Limits for the bounding rectangle in y.
... : Other arguments to be passed along as described in the last constructor method.

signature(object = "numeric", container = "matrix")

Like the previous constructor, the logs will be generated so that their centers lie within a rectangular area specified by the matrix object in the second argument. Note that ultimately, the synthetic population of logs is generated by a call to sampleLogs.

usage...

downLogs(object,
         container,
         units = 'metric',
         buttDiams = c(8, 40), 
         topDiams = c(0, 0.9), 
         logLens = c(1,10),
         logAngles = c(0, 2*pi),
         solidTypes = c(1,10),
         species = .StemEnv$species,
         ... )

object: A numeric (truncated to integer) object specifying the number of logs to generate as discussed above.
container: A matrix object specifically in the form of a bbox, bounding box object (e.g., see the sp package). It must be a 2x2 matrix with row names c("x","y") and the column names must be c("min","max"). The object specifies the internal portion of the tract within which the log centers will be generated.
units: The units of measurement.
buttDiams: A length-two vector specifying the range of butt (large-end) diameters from which to uniformly draw the sample. Note that this range is assumed to be specified in cm for metric and inches for English units.
topDiams: A length-two vector specifying the range of top (small-end) diameters in the form of a proportion of the buttDiam diameters, from which to uniformly draw the sample. See also sampleLogs.
logLens: A length-two vector specifying the range of log lengths in feet (English) or meters (metric) from which to uniformly draw the sample.
logAngles: A length-two vector specifying the range of log angles from which to draw the log lie angles; these are always counterclockwise relative to due East.
solidTypes: A length-two vector specifying the range in the log shape parameter for the default taper and volume equations; where: 1-2 is a neiloid, 2 is a cone, and >2 is a paraboloid.
species: A character vector of possible species from which to draw the sample uniformly. This can be any legal character string, and so can include codes, names, Latin names, etc.
... : Other arguments to be passed along to sampleLogs. Note specifically that one can control the random number stream by specifying a seed to be passed to sampleLogs with its startSeed argument. Additionally, this list can also contain arguments to be ultimately passed on to the downLog constructor to be applied to each individual log in the collection. For example, one can specify the number of segments desired in the taper function (nSegs) in this way.