"""
grdcontour - Plot a contour figure.
"""
from pygmt.clib import Session
from pygmt.helpers import (
build_arg_list,
deprecate_parameter,
fmt_docstring,
is_nonstr_iter,
kwargs_to_strings,
use_alias,
)
__doctest_skip__ = ["grdcontour"]
@fmt_docstring
@deprecate_parameter("interval", "levels", "v0.12.0", remove_version="v0.16.0")
@use_alias(
A="annotation",
B="frame",
C="levels",
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", 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}
levels : float, list, or str
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 0),
(**C**)ontour or (**A**)nnotate (col 1), and optional angle (col 2).
- A fixed contour interval.
- A list of contour levels.
annotation : float, list, or str
Specify or disable annotated contour levels, modifies annotated
contours specified in ``levels``.
- Specify a fixed annotation interval.
- Specify a list of annotation levels.
- Disable all annotations by setting ``annotation="n"``.
- Adjust the appearance by appending different modifiers, e.g.,
``"annot_int+f10p+gred"`` gives annotations with a font size of 10 points
and a red filled box. For all available modifiers see
:gmt-docs:`grdcontour.html#a`.
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 : str or list
[*type*]\ *pen*\ [**+c**\ [**l**\|\ **f**]].
*type*, if present, can be **a** for annotated contours or **c** for regular
contours [Default]. The pen sets the attributes for the particular line.
Default pen for annotated contours is ``"0.75p,black"`` and for regular
contours ``"0.25p,black"``. Normally, all contours are drawn with a fixed
color determined by the pen setting. If **+cl** is appended the colors of the
contour lines are taken from the CPT (see ``levels``). If **+cf** is
appended the colors from the CPT file are applied to the contour annotations.
Select **+c** for both effects.
{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 the
>>> # 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
... levels=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)
# Specify levels for the annotation and levels parameters.
# One level is converted to a string with a trailing comma to separate it from
# specifying an interval.
# Multiple levels are concatenated to a comma-separated string.
for arg in ["A", "C"]:
if is_nonstr_iter(kwargs.get(arg)):
if len(kwargs[arg]) == 1: # One level
kwargs[arg] = str(kwargs[arg][0]) + ","
else: # Multiple levels
kwargs[arg] = ",".join(f"{item}" for item in kwargs[arg])
with Session() as lib:
with lib.virtualfile_in(check_kind="raster", data=grid) as vingrd:
lib.call_module(
module="grdcontour", args=build_arg_list(kwargs, infile=vingrd)
)