gbmpred: Generate spatial predictions using generalized boosted...

In spm: Spatial Predictive Modeling

Generate spatial predictions using generalized boosted regression modeling ('gbm')

Description

This function is to make spatial predictions using generalized boosted regression modeling.

Usage

gbmpred(
  trainx,
  trainy,
  longlatpredx,
  predx,
  var.monotone = rep(0, ncol(trainx)),
  family = "gaussian",
  n.trees = 3000,
  learning.rate = 0.001,
  interaction.depth = 2,
  bag.fraction = 0.5,
  train.fraction = 1,
  n.minobsinnode = 10,
  cv.fold = 10,
  weights = rep(1, nrow(trainx)),
  keep.data = FALSE,
  verbose = TRUE,
  n.cores = 6,
  ...
)

Arguments

trainx	a dataframe or matrix contains columns of predictive variables.
trainy	a vector of response, must have length equal to the number of rows in trainx.
longlatpredx	a dataframe contains longitude and latitude of point locations (i.e., the centres of grids) to be predicted.
predx	a dataframe or matrix contains columns of predictive variables for the grids to be predicted.
var.monotone	an optional vector, the same length as the number of predictors, indicating which variables have a monotone increasing (+1), decreasing (-1), or arbitrary (0) relationship with the outcome. By default, a vector of 0 is used.
family	either a character string specifying the name of the distribution to use or a list with a component name specifying the distribution and any additional parameters needed. See 'gbm' for details. By default, "gaussian" is used.
n.trees	the total number of trees to fit. This is equivalent to the number of iterations and the number of basis functions in the additive expansion. By default, 3000 is used.
learning.rate	a shrinkage parameter applied to each tree in the expansion. Also known as step-size reduction.
interaction.depth	the maximum depth of variable interactions. 1 implies an additive model, 2 implies a model with up to 2-way interactions, etc. By default, 2 is used.
bag.fraction	the fraction of the training set observations randomly selected to propose the next tree in the expansion. By default, 0.5 is used.
train.fraction	The first 'train.fraction * nrows(data)' observations are used to fit the 'gbm' and the remainder are used for computing out-of-sample estimates of the loss function.
n.minobsinnode	minimum number of observations in the trees terminal nodes. Note that this is the actual number of observations not the total weight. By default, 10 is used.
cv.fold	integer; number of cross-validation folds to perform within 'gbm'. if > 1, then apply n-fold cross validation; the default is 10, i.e., 10-fold cross validation that is recommended.
weights	an optional vector of weights to be used in the fitting process. Must be positive but do not need to be normalized. If keep.data = FALSE in the initial call to ‘gbm' then it is the user’s responsibility to resupply the weights to 'gbm.more'. By default, a vector of 1 is used.
keep.data	a logical variable indicating whether to keep the data and an index of the data stored with the object. Keeping the data and index makes subsequent calls to 'gbm.more' faster at the cost of storing an extra copy of the dataset. By default, 'FALSE' is used.
verbose	If TRUE, 'gbm' will print out progress and performance indicators. By default, 'TRUE' is used.
n.cores	The number of CPU cores to use. See 'gbm' for details. By default, 6 is used.
...	other arguments passed on to 'gbm'.

Value

A dataframe of longitude, latitude and predictions.

Note

This function is largely based on 'gbm'.

Author(s)

Jin Li

References

Greg Ridgeway with contributions from others (2015). gbm: Generalized Boosted Regression Models. R package version 2.1.1. https://CRAN.R-project.org/package=gbm

Examples

## Not run: 
data(sponge)
data(sponge.grid)
gbmpred1 <- gbmpred(sponge[, -c(3)], sponge[, 3], sponge.grid[, c(1:2)],
sponge.grid, family = "poisson", n.cores=2)
names(gbmpred1)

## End(Not run)

spm documentation built on May 6, 2022, 9:06 a.m.