Finding contours of a map

This example shows how to find and plot contours on a map.

import matplotlib.pyplot as plt

import astropy.units as u

import sunpy.map
from sunpy.data.sample import AIA_193_IMAGE

Start by loading the sample data.

aiamap = sunpy.map.Map(AIA_193_IMAGE)

In finding a set of contours, we have to provide the level to contour in the same units as the map data. To find out the units we can inspect sunpy.map.GenericMap.unit.

print(aiamap.unit)

Out:

ct

We can see that the units of this map are ct, or counts. We can now chose a contour level, and use the contour() method to extract the contours.

contours = aiamap.contour(50000 * u.ct)

Finally, we can plot the map, and add each of the contours in turn.

plt.figure()
ax = plt.subplot(projection=aiamap)
aiamap.plot()
for contour in contours:
    ax.plot_coord(contour)
plt.show()
AIA $193 \; \mathrm{\mathring{A}}$ 2011-06-07 06:33:07

Total running time of the script: ( 0 minutes 1.253 seconds)

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