pygmt.grdcut

pygmt.grdcut(grid, **kwargs)[source]

Extract subregion from a grid.

Produce a new outgrid file which is a subregion of grid. The subregion is specified with region; the specified range must not exceed the range of grid (but see extend). If in doubt, run pygmt.grdinfo to check range. Alternatively, define the subregion indirectly via a range check on the node values or via distances from a given point. Finally, you can give projection for oblique projections to determine the corresponding rectangular region setting that will give a grid that fully covers the oblique domain.

Full option list at https://docs.generic-mapping-tools.org/latest/grdcut.html

Aliases:

  • G = outgrid

  • J = projection

  • N = extend

  • R = region

  • S = circ_subregion

  • Z = z_subregion

Parameters

  • grid (str or xarray.DataArray) – The file name of the input grid or the grid loaded as a DataArray.

  • outgrid (str or None) – The name of the output netCDF file with extension .nc to store the grid in.

  • projection (str) – Required if this is the first plot command. Select map projection.

  • region (str or list) – Required if this is the first plot command. 'xmin/xmax/ymin/ymax[+r][+uunit]'. Specify the region of interest.

  • extend (bool or int or float) – Allow grid to be extended if new region exceeds existing boundaries. Give a value to initialize nodes outside current region.

  • circ_subregion (str) – 'lon/lat/radius[unit][+n]'. Specify an origin (lon and lat) and radius; append a distance unit and we determine the corresponding rectangular region so that all grid nodes on or inside the circle are contained in the subset. If +n is appended we set all nodes outside the circle to NaN.

  • z_subregion (str) – '[min/max][+n|N|r]'. Determine a new rectangular region so that all nodes outside this region are also outside the given z-range [-inf/+inf]. To indicate no limit on min or max only, specify a hyphen (-). Normally, any NaNs encountered are simply skipped and not considered in the range-decision. Append +n to consider a NaN to be outside the given z-range. This means the new subset will be NaN-free. Alternatively, append +r to consider NaNs to be within the data range. In this case we stop shrinking the boundaries once a NaN is found [Default simply skips NaNs when making the range decision]. Finally, if your core subset grid is surrounded by rows and/or columns that are all NaNs, append +N to strip off such columns before (optionally) considering the range of the core subset for further reduction of the area.

Returns

ret (xarray.DataArray or None) – Return type depends on whether the outgrid parameter is set:

  • xarray.DataArray if outgrid is not set

  • None if outgrid is set (grid output will be stored in outgrid)