7. Plotting point data

PolarToolkit also supports some plotting of point data (non-gridded). Here we will download a dataset and make a simple plot.

Import the necessary modules

%load_ext autoreload
%autoreload 2

from polartoolkit import fetch, maps, regions

Fetch a pandas dataframe of point measurements of Antarctic geothermal heat flux.

df = fetch.ghf(version="burton-johnson-2020", region=regions.victoria_land, points=True)
df.describe()

	lat	lon	top (m)	GHF	Elevation (m.a.s.l.)	x	y
count	40.000000	40.000000	21.000000	40.00000	27.000000	40.000000	4.000000e+01
mean	-76.651405	164.625446	79.515238	93.96425	-511.370370	385506.781862	-1.403849e+06
std	1.022481	2.106831	83.861870	32.56072	516.276994	56561.159260	1.114094e+05
min	-77.889444	158.840000	0.000000	25.00000	-1060.000000	295055.798355	-1.659851e+06
25%	-77.579550	163.511700	1.520000	74.57500	-889.000000	350410.933318	-1.470873e+06
50%	-76.887990	164.990000	60.000000	91.50000	-870.000000	390975.335529	-1.383358e+06
75%	-76.040000	166.108330	150.000000	117.00000	48.000000	397751.013322	-1.298559e+06
max	-74.483300	168.166700	260.000000	167.47000	349.000000	561346.437658	-1.287180e+06

Use the basemap function to make a figure instance, and add the points to that.

fig = maps.basemap(
    region=regions.victoria_land,
    title="Geothermal Heat Flux",
    imagery_basemap=True,
    imagery_transparency=50,
    coast=True,
    hemisphere="south",
    points=df,
    points_cmap="magma",
    points_fill="GHF",
    points_pen=".2p,black",
    colorbar=True,
    hist=True,
    hist_bin_num=15,
    cbar_label="mW/m@+2@+",
)

fig.show(dpi=200)

grdimage [WARNING]: (w - x_min) must equal (NX + eps) * x_inc), where NX is an integer and |eps| <= 0.0001.
grdimage [WARNING]: w reset from 100000 to 99766.1470198
grdimage [WARNING]: (e - x_min) must equal (NX + eps) * x_inc), where NX is an integer and |eps| <= 0.0001.
grdimage [WARNING]: e reset from 1000000 to 1000045.54542
grdimage [WARNING]: (s - y_min) must equal (NY + eps) * y_inc), where NY is an integer and |eps| <= 0.0001.
grdimage [WARNING]: s reset from -2200000 to -2200065.03982
grdimage [WARNING]: (n - y_min) must equal (NY + eps) * y_inc), where NY is an integer and |eps| <= 0.0001.
grdimage [WARNING]: n reset from -1000000 to -999825.037242