GDALReadOnlyDataset-methods      package:rgdal      R Documentation

_s_u_b_s_e_t _m_e_t_h_o_d_s _f_o_r "_G_D_A_L_R_e_a_d_O_n_l_y_D_a_t_a_s_e_t"

_D_e_s_c_r_i_p_t_i_o_n:

     subsets GDAL objects, returning a SpatialGridDataFrame object

_D_e_t_a_i_l_s:

     subsets a GDAL data set, returning a SpatialGridDataFrame object.
     Reading is done on the GDAL side, and only the subset requested is
     ever read into memory.

     Further named arguments to '[' are to either getRasterTable or
     getRasterData:

     _a_s._i_s see getRasterData

     _i_n_t_e_r_l_e_a_v_e see getRasterData

     _o_u_t_p_u_t._d_i_m see getRasterData

     the other arguments, 'offset' and 'region.dim' are derived from
     row/column selection values.

_M_e_t_h_o_d_s:

     "[" 'signature(.Object = "GDALReadOnlyDataset")': requires package
          sp; selects rows and columns, and returns an object of class
          SpatialGridDataFrame if the grid is not rotated, or else of
          class SpatialPointsDataFrame. Any arguments passed to
          getRasterData (or in case of rotation getRasterTable) may be
          passed as named arguments; the first three unnamed arguments
          are row,col,band 

_A_u_t_h_o_r(_s):

     Edzer J. Pebesma

_S_e_e _A_l_s_o:

     See also 'readGDAL' 'GDALDriver-class', 'GDALDataset-class',
     'GDALTransientDataset-class', 'SpatialGridDataFrame-class' .

_E_x_a_m_p_l_e_s:

     logo <- system.file("pictures/logo.jpg", package="rgdal")[1]
     x <- new("GDALReadOnlyDataset", logo)
     dim(x)
     x.sp = x[20:50, 20:50]
     class(x.sp)
     summary(x.sp)
     spplot(x.sp)
     GDAL.close(x)

     logo <- system.file("pictures/Rlogo.jpg", package="rgdal")[1]
     x.gdal <- new("GDALReadOnlyDataset", logo)
     x = x.gdal[,,3]
     dim(x)
     summary(x)
     spplot(x)
     spplot(x.gdal[])
     GDAL.close(x.gdal)

