stress2grid function

Spatial Interpolation of SHmax

Stress field interpolation and wavelength analysis using a kernel (weighted) mean/median and standard deviation/IQR of stress data

Source

https://github.com/MorZieg/Stress2Grid

stress2grid(
  x,
  stat = c("mean", "median"),
  grid = NULL,
  lon_range = NULL,
  lat_range = NULL,
  gridsize = 2,
  min_data = 3L,
  threshold = 25,
  arte_thres = 200,
  method_weighting = FALSE,
  quality_weighting = TRUE,
  dist_weight = c("inverse", "linear", "none"),
  idp = 1,
  qp = 1,
  mp = 1,
  dist_threshold = 0.1,
  R_range = seq(50, 1000, 50),
  ...
)

stress2grid_stats(
  x,
  grid = NULL,
  lon_range = NULL,
  lat_range = NULL,
  gridsize = 2,
  min_data = 4L,
  threshold = 25,
  arte_thres = 200,
  method_weighting = FALSE,
  quality_weighting = TRUE,
  dist_weight = c("inverse", "linear", "none"),
  idp = 1,
  qp = 1,
  mp = 1,
  dist_threshold = 0.1,
  R_range = seq(50, 1000, 50),
  kappa = NULL,
  ...
)

Arguments

• x: sf object containing

  • azi: SHmax in degree
  • unc: (optional) Uncertainties of SHmax in degree
  • type: (optional) Methods used for the determination of the direction of SHmax

• stat: whether the direction of interpolated SHmax is based on the circular mean and standard deviation ("mean", the default) or the circular median and interquartile range ("median")

• grid: (optional) Point object of class sf.

• lon_range, lat_range: (optional) numeric vector specifying the minimum and maximum longitudes and latitudes (ignored if grid is specified).

• gridsize: numeric. Target spacing of the regular grid in decimal degree. Default is 2.5. (is ignored if grid is specified)

• min_data: integer. Minimum number of data per bin. Default is 3 for stress2grid()and 4 for stress2grid_stats().

• threshold: numeric. Threshold for deviation of direction. Default is 25

• arte_thres: numeric. Maximum distance (in km) of the grid point to the next data point. Default is 200

• method_weighting: logical. If a method weighting should be applied: Default is FALSE. If FALSE, overwrites mp.

• quality_weighting: logical. If a quality weighting should be applied: Default is TRUE. If FALSE, overwrites qp.

• dist_weight: Distance weighting method which should be used. One of "none", "linear", or "inverse" (the default).

• idp, qp, mp: numeric. The weighting power of inverse distance, quality and method. Default is 1. The higher the value, the more weight it will put. When set to 0, no weighting is applied. idp is only effective if inverse distance weighting (dist_weight="inverse") is applied.

• dist_threshold: numeric. Distance weight to prevent overweight of data nearby (0 to 1). Default is 0.1

• R_range: numeric value or vector specifying the kernel half-width(s), i.e. the search radius (in km). Default is seq(50, 1000, 50)

• ...: (optional) arguments to dist_greatcircle()

• kappa: numeric. von Mises distribution concentration parameter used for the circular mode. Will be estimated using est.kappa() if not provided.

Returns

sf object containing

• lon,lat: longitude and latitude in degrees
• azi: Mean SHmax in degree
• sd: Standard deviation of SHmax in degrees
• R: Search radius in km
• mdr: Mean distance of datapoints per search radius
• N: Number of data points in search radius

When stress2grid_stats(), azi and sd are replaced by the output of circular_summary().

Details

stress2grid() is a modified version of the MATLAB script "stress2grid" by Ziegler and Heidbach (2019). stress2grid_stats() is based on stress2grid() but yields more circular summary statistics (see circular_summary()).

Examples

data("san_andreas")
stress2grid(san_andreas, stat = "median")
## Not run:

stress2grid_stats(san_andreas)
## End(Not run)

References

Ziegler, M. and Heidbach, O. (2019). Matlab Script Stress2Grid v1.1. GFZ Data Services. tools:::Rd_expr_doi("10.5880/wsm.2019.002")

See Also

dist_greatcircle(), PoR_stress2grid(), compact_grid(), circular_mean(), circular_median(), circular_sd(), circular_summary()