How to plot a circle?

[pan3rock]

I would like to plot a circle with (lat, lon, radius), search for it in google. It seems that gmt psxy pratt.txt -R -J -O -K -SE- -Wthinnest >> $ps and how to implement it by pygmt?

    import pygmt
    region = "-180/180/-90/-60"
    projection = "s0/-90/-71/1:33000000"
    fig = pygmt.Figure()
    fig.coast(region=region,
                  projection=projection,
                  frame='afg',
                  resolution='i',
                  shorelines='0.3p')
    fig.plot([170], [-80], sizes=[200], style='E') # not work

[weiji14]

Hi @pan3rock,

Great to see another Antarctic scientist . You’re actually just missing a dash ‘-’ in the command (should be style="E-"), and probably need to set a pen too. Try this:

import pygmt

region = [-180, 180, -90, -60]
projection = "s0/-90/-71/1:33000000"
fig = pygmt.Figure()
fig.coast(
    region=region, projection=projection, frame="afg", resolution="i", shorelines="0.3p"
)
fig.plot(x=[170], y=[-80], sizes=[200], style="E-", pen="1.5p,purple2")
fig.show()

produces:

By the way, you can also plot the grounding line using area_thresh="+ag" (see coast’s -A option), and label you study area like so:

import pygmt

region = [-180, 180, -90, -60]
projection = "s0/-90/-71/1:33000000"
fig = pygmt.Figure()
fig.coast(
    region=region,
    projection=projection,
    area_thresh="+ag",
    frame="afg",
    resolution="i",
    shorelines="0.3p",
)
fig.plot(
    x=[170],
    y=[-80],
    sizes=[200],
    style="E-",
    pen="1.5p,purple2",
    label='"Ross Ice Shelf study area"',
)
fig.legend()
fig.show()

produces:

Let me know if that helps. There doesn’t seem to be a way to simultaneously plot both the ice shelf ‘coastline’ and grounding line (using -Aig) but we could raise that as a feature request

[pan3rock]

Thank you very much. I’m trying to add plotting functional to my python codes and your answer helps me a lot.