create_PolyGrids: Create a Polygon Grid
In CCAMLRGIS: Antarctic Spatial Data Manipulation

create_PolyGrids

R Documentation

Create a Polygon Grid

Description

Create a polygon grid to spatially aggregate data in cells of chosen size. Cell size may be specified in degrees or as a desired area in square kilometers (in which case cells are of equal area). Using Blank=TRUE (with caution) produces an empty grid.

Usage

create_PolyGrids(
  Input,
  NamesIn = NULL,
  dlon = NA,
  dlat = NA,
  Area = NA,
  cuts = 100,
  cols = c("green", "yellow", "red"),
  Blank = FALSE
)

Arguments

`Input`	input dataframe. If `NamesIn` is not provided, the columns in the `Input` must be in the following order: Latitude, Longitude, Variable 1, Variable 2 ... Variable x.
`NamesIn`	character vector of length 2 specifying the column names of Latitude and Longitude fields in the `Input`. Latitudes name must be given first, e.g.: `NamesIn=c('MyLatitudes','MyLongitudes')`.
`dlon`	numeric, width of the grid cells in decimal degrees of longitude.
`dlat`	numeric, height of the grid cells in decimal degrees of latitude.
`Area`	numeric, area in square kilometers of the grid cells. The smaller the `Area`, the longer it will take.
`cuts`	numeric, number of desired color classes.
`cols`	character, desired colors. If more that one color is provided, a linear color gradient is generated.
`Blank`	logical, `TRUE` or `FALSE`. If `TRUE`, creates an empty grid spanning the bounding box given in the `Input` as: `c(LatMin,LatMax,LonMin,LonMax)`. The script might struggle to reach equal-area gridding if the desired cell `Area` is too large, and/or the `Input` bounding box is too small, and/or the `Input` bounding box does not span -180 to 180 degrees longitude. Use `Blank=TRUE` with caution.

Value

Spatial object in your environment.

if Blank=FALSE:

Data within the resulting spatial object contains the data provided in the Input after aggregation within cells. For each Variable, the minimum, maximum, mean, sum, count, standard deviation, and, median of values in each cell is returned. In addition, for each cell, its area (AreaKm2), projected centroid (Centrex, Centrey) and unprojected centroid (Centrelon, Centrelat) is given. Also, colors are generated for each aggregated values according to the chosen cuts and cols. To generate a custom color scale after the grid creation, refer to add_col and add_Cscale.

if Blank=TRUE:

An empty grid is generated. It can be re-used across scripts in conjunction with assign_areas.

Examples



# For more examples, see:
# https://github.com/ccamlr/CCAMLRGIS#create-grids
# And:
# https://github.com/ccamlr/CCAMLRGIS/blob/master/Advanced_Grids/Advanced_Grids.md

#Simple grid, using automatic colors

MyGrid=create_PolyGrids(Input=GridData,dlon=2,dlat=1)
#View(MyGrid)
plot(st_geometry(MyGrid),col=MyGrid$Col_Catch_sum)

CCAMLRGIS documentation built on March 3, 2026, 9:08 a.m.