- pygmt.grdsample(grid, *, outgrid=None, spacing=None, region=None, translate=None, verbose=None, coltypes=None, interpolation=None, registration=None, cores=None, **kwargs)[source]
Change the registration, spacing, or nodes in a grid file.
This reads a grid file and interpolates it to create a new grid file. It can change the registration with
registration, change the grid-spacing or number of nodes with
spacing, and set a new sub-region using
region. A bicubic [Default], bilinear, B-spline or nearest-neighbor interpolation is set with
regionis omitted, the output grid will cover the same region as the input grid. When
spacingis omitted, the grid spacing of the output grid will be the same as the input grid. Either
translatecan be used to change the grid registration. When omitted, the output grid will have the same registration as the input grid.
Full option list at https://docs.generic-mapping-tools.org/latest/grdsample.html
G = outgrid
I = spacing
R = region
T = translate
V = verbose
f = coltypes
n = interpolation
r = registration
x = cores
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.
spacing (str) –
x_inc[+e|n][/y_inc[+e|n]]. x_inc [and optionally y_inc] is the grid spacing.
Geographical (degrees) coordinates: Optionally, append an increment unit. Choose among m to indicate arc-minutes or s to indicate arc-seconds. If one of the units e, f, k, M, n or u is appended instead, the increment is assumed to be given in meter, foot, km, mile, nautical mile or US survey foot, respectively, and will be converted to the equivalent degrees longitude at the middle latitude of the region (the conversion depends on PROJ_ELLIPSOID). If y_inc is given but set to 0 it will be reset equal to x_inc; otherwise it will be converted to degrees latitude.
All coordinates: If +e is appended then the corresponding max x (east) or y (north) may be slightly adjusted to fit exactly the given increment [by default the increment may be adjusted slightly to fit the given domain]. Finally, instead of giving an increment you may specify the number of nodes desired by appending +n to the supplied integer argument; the increment is then recalculated from the number of nodes, the
registration, and the domain. The resulting increment value depends on whether you have selected a gridline-registered or pixel-registered grid; see GMT File Formats for details.
region=grdfileis used then the grid spacing and the registration have already been initialized; use
registrationto override these values.
region (str or list) – xmin/xmax/ymin/ymax[+r][+uunit]. Specify the region of interest.
translate (bool) – Translate between grid and pixel registration; if the input is grid-registered, the output will be pixel-registered and vice-versa.
registration (str or bool) – [g|p]. Set registration to gridline or pixel.
Select verbosity level [Default is w], which modulates the messages written to stderr. Choose among 7 levels of verbosity:
q - Quiet, not even fatal error messages are produced
e - Error messages only
w - Warnings [Default]
t - Timings (report runtimes for time-intensive algorithms)
i - Informational messages (same as
c - Compatibility warnings
d - Debugging messages
coltypes (str) – [i|o]colinfo. Specify data types of input and/or output columns (time or geographical data). Full documentation is at https://docs.generic-mapping-tools.org/latest/gmt.html#f-full.
interpolation (str) –
[b|c|l|n][+a][+bBC][+c][+tthreshold]. Select interpolation mode for grids. You can select the type of spline used:
b for B-spline
c for bicubic [Default]
l for bilinear
n for nearest-neighbor
cores (bool or int) – [[-]n]. Limit the number of cores to be used in any OpenMP-enabled multi-threaded algorithms. By default we try to use all available cores. Set a number n to only use n cores (if too large it will be truncated to the maximum cores available). Finally, give a negative number -n to select (all - n) cores (or at least 1 if n equals or exceeds all).
ret (xarray.DataArray or None) – Return type depends on whether the
outgridparameter is set:
outgridis not set
outgridis set (grid output will be stored in file set by
>>> import pygmt >>> # Load a grid of @earth_relief_30m data, with an x-range of 10 to 30, >>> # and a y-range of 15 to 25 >>> grid = pygmt.datasets.load_earth_relief( ... resolution="30m", region=[10, 30, 15, 25] ... ) >>> # Create a new grid from an input grid, change the registration, >>> # and set both x- and y-spacing to 0.5 degrees >>> new_grid = pygmt.grdsample( ... grid=grid, translate=True, spacing=[0.5, 0.5] ... )