"""
grdcontour - Plot a contour figure.
"""
from pygmt.clib import Session
from pygmt.helpers import build_arg_string, fmt_docstring, kwargs_to_strings, use_alias
__doctest_skip__ = ["grdcontour"]
@fmt_docstring
@use_alias(
A="annotation",
B="frame",
C="interval",
G="label_placement",
J="projection",
L="limit",
Q="cut",
R="region",
S="resample",
V="verbose",
W="pen",
l="label",
c="panel",
f="coltypes",
p="perspective",
t="transparency",
)
@kwargs_to_strings(
R="sequence", L="sequence", A="sequence_plus", c="sequence_comma", p="sequence"
)
def grdcontour(self, grid, **kwargs):
r"""
Convert grids or images to contours and plot them on maps.
Takes a grid file name or an xarray.DataArray object as input.
Full option list at :gmt-docs:`grdcontour.html`
{aliases}
Parameters
----------
{grid}
interval : str or int
Specify the contour lines to generate.
- The file name of a CPT file where the color boundaries will
be used as contour levels.
- The file name of a 2 (or 3) column file containing the contour
levels (col 1), (**C**)ontour or (**A**)nnotate (col 2), and optional
angle (col 3).
- A fixed contour interval *cont_int* or a single contour with
+\ *cont_int*.
annotation : str, int, or list
Specify or disable annotated contour levels, modifies annotated
contours specified in ``interval``.
- Specify a fixed annotation interval *annot_int* or a
single annotation level +\ *annot_int*.
- Disable all annotation with **-**.
- Optional label modifiers can be specified as a single string
``"[annot_int]+e"`` or with a list of arguments
``([annot_int], "e", "f10p", "gred")``.
limit : str or list of 2 ints
*low*/*high*.
Do no draw contours below `low` or above `high`, specify as string
cut : str or int
Do not draw contours with less than `cut` number of points.
resample : str or int
Resample smoothing factor.
{projection}
{region}
{frame}
label_placement : str
[**d**\|\ **f**\|\ **n**\|\ **l**\|\ **L**\|\ **x**\|\ **X**]\
*args*.
Control the placement of labels along the quoted lines. It supports
five controlling algorithms. See :gmt-docs:`grdcontour.html#g` for
details.
{verbose}
{pen}
{panel}
{coltypes}
label : str
Add a legend entry for the contour being plotted. Normally, the
annotated contour is selected for the legend. You can select the
regular contour instead, or both of them, by considering the label
to be of the format [*annotcontlabel*][/*contlabel*]. If either
label contains a slash (/) character then use ``|`` as the
separator for the two labels instead.
{perspective}
{transparency}
Example
-------
>>> import pygmt
>>> # load the 15 arc-minutes grid with "gridline" registration
>>> # in a specified region
>>> grid = pygmt.datasets.load_earth_relief(
... resolution="15m",
... region=[-92.5, -82.5, -3, 7],
... registration="gridline",
... )
>>> # create a new plot with pygmt.Figure()
>>> fig = pygmt.Figure()
>>> # create the contour plot
>>> fig.grdcontour(
... # pass in the grid downloaded above
... grid=grid,
... # set the interval for contour lines at 250 meters
... interval=250,
... # set the interval for annotated contour lines at 1,000 meters
... annotation=1000,
... # add a frame for the plot
... frame="a",
... # set the projection to Mercator for the 10 cm figure
... projection="M10c",
... )
>>> # show the plot
>>> fig.show()
"""
kwargs = self._preprocess(**kwargs)
with Session() as lib:
file_context = lib.virtualfile_from_data(check_kind="raster", data=grid)
with file_context as fname:
lib.call_module(
module="grdcontour", args=build_arg_string(kwargs, infile=fname)
)