optimal parameters-based geographical detector(OPGD) model

Usage

opgd(
  formula,
  data,
  discvar = NULL,
  discnum = 3:8,
  discmethod = c("sd", "equal", "geometric", "quantile", "natural"),
  cores = 1,
  type = "factor",
  alpha = 0.95,
  ...
)

Arguments

formula: A formula of OPGD model.
data: A data.frame, tibble or sf object of observation data.
discvar: Name of continuous variable columns that need to be discretized. Noted that when formula has discvar, data must have these columns. By default, all independent variables are used as discvar.
discnum: (optional) A vector of number of classes for discretization. Default is 3:8.
discmethod: (optional) A vector of methods for discretization, default is using c("sd","equal","geometric","quantile","natural") by invoking sdsfun.
cores: (optional) Positive integer (default is 1). When cores are greater than 1, use multi-core parallel computing.
type: (optional) The type of geographical detector, which must be factor(default), interaction, risk, ecological. You can run one or more types at one time.
alpha: (optional) Specifies the size of confidence level. Default is 0.95.
...: (optional) Other arguments passed to gd_optunidisc(). A useful parameter is seed, which is used to set the random number seed.

Value

A list.

opt_param: optimal discretization parameter
factor: the result of factor detector
interaction: the result of interaction detector
risk: the result of risk detector
ecological: the result of ecological detector

References

Song, Y., Wang, J., Ge, Y. & Xu, C. (2020) An optimal parameters-based geographical detector model enhances geographic characteristics of explanatory variables for spatial heterogeneity analysis: Cases with different types of spatial data, GIScience & Remote Sensing, 57(5), 593-610. doi: 10.1080/15481603.2020.1760434.

Author

Wenbo Lv lyu.geosocial@gmail.com

Examples

data('sim')
opgd(y ~ xa + xb + xc, data = sim,
     discvar = paste0('x',letters[1:3]),
     discnum = 3:6)
#> ***   Optimal Parameters-based Geographical Detector     
#>                 Factor Detector            
#> 
#> | variable | Q-statistic |   P-value   |
#> |:--------:|:-----------:|:-----------:|
#> |    xc    |  0.6225785  | 5.72000e-10 |
#> |    xb    |  0.4800064  | 1.00905e-07 |
#> |    xa    |  0.3267163  | 7.64250e-05 |
#>