pygmt.grdtrack(points, grid, newcolname=None, outfile=None, **kwargs)[source]

Sample grids at specified (x,y) locations.

Grdtrack reads one or more grid files and a table with (x,y) [or (lon,lat)] positions in the first two columns (more columns may be present). It interpolates the grid(s) at the positions in the table and writes out the table with the interpolated values added as (one or more) new columns. A bicubic [Default], bilinear, B-spline or nearest-neighbor (see -n) interpolation is used, requiring boundary conditions at the limits of the region.

Full option list at

  • points (pandas.DataFrame or file (csv, txt, etc)) – Either a table with (x, y) or (lon, lat) values in the first two columns, or a data file name. More columns may be present.

  • grid (xarray.DataArray or file (netcdf)) – Gridded array from which to sample values from.

  • newcolname (str) – Required if ‘points’ is a pandas.DataFrame. The name for the new column in the track pandas.DataFrame table where the sampled values will be placed.

  • outfile (str) – Required if ‘points’ is a file. The file name for the output ASCII file.


track (pandas.DataFrame or None) – Return type depends on whether the outfile parameter is set:

  • pandas.DataFrame table with (x, y, …, newcolname) if outfile is not set

  • None if outfile is set (track output will be stored in outfile)