# Filter the best classified occurrences within grid cells

With `grid_filter()` you may filter occurrence records inside grid cells in order to keep only the record with the highest confidence level in each grid cell.

Fig. 1 - The procedure of `grid_filter()` to select the record with the highest confidence level in each grid cell

As example, we will filter the `occ.class` in square grid cells of 0.5 decimal degree of side, which is the default grid cell size of `grid_filter()`. You can provide the height and width of the grid cell in `grid.resolution` argument, or provide a raster layer in argument `r` from which the cell is used to filter occurrences.

    # Load package and data
    library(naturaList)

    data("A.setosa")
    data("speciaLists")

    # classification
    occ.class <- classify_occ(A.setosa, speciaLists)

    # grid filtering
    occ.grid <- grid_filter(occ.class)

    dim(occ.grid)
    table(occ.grid$naturaList_levels)