Note
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Setting the region
Many of the plotting methods take the region
parameter, which sets the
area that will be shown in the figure. This tutorial covers the different types
of inputs that it can accept.
import pygmt
Coordinates
A string of coordinates can be passed to region
, in the form of
xmin/xmax/ymin/ymax.
fig = pygmt.Figure()
fig.coast(
# Set the x-range from 10E to 20E and the y-range to 35N to 45N
region="10/20/35/45",
# Set projection to Mercator, and the figure size to 15 centimeters
projection="M15c",
# Set the color of the land to light gray
land="lightgray",
# Set the color of the water to white
water="white",
# Display the national borders and set the pen thickness to 0.5p
borders="1/0.5p",
# Display the shorelines and set the pen thickness to 0.5p
shorelines="1/0.5p",
# Set the frame to display annotations and gridlines
frame="ag",
)
fig.show()
The coordinates can be passed to region
as a list, in the form of
[xmin, xmax, ymin, ymax].
fig = pygmt.Figure()
fig.coast(
# Set the x-range from 10E to 20E and the y-range to 35N to 45N
region=[10, 20, 35, 45],
projection="M12c",
land="lightgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
Instead of passing axes minima and maxima, the coordinates can be passed for
the bottom-left and top-right corners. The string format takes the
coordinates for the bottom-left and top-right coordinates. To specify corner
coordinates, append +r at the end of the region
string.
fig = pygmt.Figure()
fig.coast(
# Set the bottom-left corner as 10E, 35N and the top-right corner as
# 20E, 45N
region="10/35/20/45+r",
projection="M12c",
land="lightgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
Global regions
In addition to passing coordinates, the argument d can be passed to set the region to the entire globe. The range is 180W to 180E (-180, 180) and 90S to 90N (-90 to 90). With no parameters set for the projection, the figure defaults to be centered at the mid-point of both x- and y-axes. Using d, the figure is centered at (0, 0), or the intersection of the equator and prime meridian.
fig = pygmt.Figure()
fig.coast(
region="d",
projection="Cyl_stere/12c",
land="darkgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
The argument g can be passed, which encompasses the entire globe. The range is 0E to 360E (0, 360) and 90S to 90N (-90 to 90). With no parameters set for the projection, the figure is centered at (180, 0), or the intersection of the equator and International Date Line.
fig = pygmt.Figure()
fig.coast(
region="g",
projection="Cyl_stere/12c",
land="darkgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
ISO code
The region
can be set to include a specific area specified by the
two-character ISO 3166-1 alpha-2 convention
(for further information: https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2).
fig = pygmt.Figure()
fig.coast(
# Set the figure region to encompass Japan with the ISO code "JP"
region="JP",
projection="M12c",
land="lightgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
The area encompassed by the ISO code can be expanded by appending +rincrement to the ISO code. The increment unit is in degrees, and if only one value is added it expands the range of the region in all directions. Using +r expands the final region boundaries to be multiples of increment .
fig = pygmt.Figure()
fig.coast(
# Expand the region boundaries to be multiples of 3 degrees in all
# directions
region="JP+r3",
projection="M12c",
land="lightgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
Instead of expanding the range of the plot uniformly in all directions, two values can be passed to expand differently on each axis. The format is xinc/yinc.
fig = pygmt.Figure()
fig.coast(
# Expand the region boundaries to be multiples of 3 degrees on the x-axis
# and 5 degrees on the y-axis.
region="JP+r3/5",
projection="M12c",
land="lightgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
Instead of expanding the range of the plot uniformly in all directions, four values can be passed to expand differently in each direction. The format is winc/einc/sinc/ninc, which expands on the west, east, south, and north axes.
fig = pygmt.Figure()
fig.coast(
# Expand the region boundaries to be multiples of 3 degrees to the west, 5
# degrees to the east, 7 degrees to the south, and 9 degrees to the north.
region="JP+r3/5/7/9",
projection="M12c",
land="lightgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
The region
increment can be appended with +R, which adds the
increment without rounding.
fig = pygmt.Figure()
fig.coast(
# Expand the region setting outside the range of Japan by 3 degrees in all
# directions, without rounding to the nearest increment.
region="JP+R3",
projection="M12c",
land="lightgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
The region
increment can be appended with +e, which is like +r
and expands the final region boundaries to be multiples of increment.
However, it ensures that the bounding box extends by at least 0.25 times the
increment.
fig = pygmt.Figure()
fig.coast(
# Expand the region boundaries to be multiples of 3 degrees in all
# directions
region="JP+e3",
projection="M12c",
land="lightgray",
water="white",
borders="1/0.5p",
shorelines="1/0.5p",
frame="ag",
)
fig.show()
Total running time of the script: ( 0 minutes 7.935 seconds)