Add fix_earth parameter to SolarMACH.plot() for longitude orientation control

examples/example.ipynb

@@ -1783,15 +1783,18 @@
     "plot_sun_body_line = False          # plot straight line between Sun and body\n",
     "transparent = False                 # make output figure background transparent\n",
     "markers = 'numbers'                 # use 'numbers' or 'letters' for the body markers (use False for colored squares)\n",
+    "coord_sys='Stonyhurst'              # 'Carrington' (default) or 'Stonyhurst'\n",
+    "fix_earth=True                      # if True, Earth is always at a fixed longitude position. If False, the plot is oriented with 0° fixed.  \n",
     "\n",
     "for i in range(2,19,1):    \n",
     "    j = str(i).rjust(2, '0')\n",
     "    date = f'2022-6-{j} 12:00:00'\n",
     "    filename = f'animate_{date[:-9]}.png'        # define filename of output figure\n",
     "\n",
-    "    sm7 = SolarMACH(date=date, body_list=body_list, vsw_list=vsw_list, coord_sys='Stonyhurst')\n",
+    "    sm7 = SolarMACH(date=date, body_list=body_list, vsw_list=vsw_list, coord_sys=coord_sys)\n",
     "    sm7.plot(plot_spirals=plot_spirals,\n",
     "             plot_sun_body_line=plot_sun_body_line,\n",
+    "             fix_earth=fix_earth,\n",
     "             transparent=transparent,\n",
     "             markers=markers,\n",
     "             outfile=filename\n",
@@ -1824,7 +1827,7 @@
    "source": [
     "Build an animated GIF out of these files using `imageio`. \n",
     "\n",
-    "Note: Using `coord_sys'=Carrington'` above may lead to unexpected behavior while generating the GIF. It's advised to use `coord_sys='Stonyhurst'` for this purpose."
+    "Note: The `fix_earth` option above should be changed according to the used coordinate system. For `coord_sys'=Carrington'`, you should use `fix_earth=False`; for `coord_sys='Stonyhurst'` `fix_earth=True`. Otherwise the coordinate systems will be mixed up in the animation."
    ]
   },
   {

solarmach/__init__.py

@@ -586,6 +586,7 @@ def plot(self, plot_spirals=True,
              transparent=False,
              markers=False,
              return_plot_object=False,
+             fix_earth=True,
              long_offset=270,
              outfile='',
              figsize=(12, 8),
@@ -621,8 +622,10 @@ def plot(self, plot_spirals=True,
             if defined, body markers contain 'numbers' or 'letters' for better identification. If False (default), only geometric markers are used.
         return_plot_object : bool, optional
             if True, figure and axis object of matplotib are returned, allowing further adjustments to the figure
+        fix_earth : bool, optional
+            if True (default), Earth is always at the defined long_offset position (by default "6 o'clock", i.e., 270°). If False, the plot is oriented with 0° at the position defined with long_offset.
         long_offset : int or float, optional
-            longitudinal offset for polar plot; defines where Earth's longitude is (by default 270, i.e., at "6 o'clock")
+            longitudinal offset for polar plot; defines for fix_earth=True (default) where Earth's longitude is (by default 270, i.e., at "6 o'clock"). For fix_earth=False it defines where 0° is located.
         outfile : string, optional
             if provided, the plot is saved with outfile as filename. supports png and pdf format.
         long_sector : list of 2 numbers, optional
@@ -681,7 +684,10 @@ def plot(self, plot_spirals=True,
 
         rlabel_pos = E_long + 120
         ax.set_rlabel_position(rlabel_pos)
-        ax.set_theta_offset(np.deg2rad(long_offset - E_long))
+        if fix_earth:
+            ax.set_theta_offset(np.deg2rad(long_offset - E_long))
+        elif not fix_earth:
+            ax.set_theta_offset(np.deg2rad(long_offset))
         ax.yaxis.get_major_locator().base.set_params(nbins=4)
         circle = plt.Circle((0., 0.),
                             self.max_dist + 0.29,

solarmach/tests/figure_hashes_mpl_391.json

@@ -1,4 +1,5 @@
 {
-  "solarmach.tests.test.test_solarmach_plot": "53086961f48868f8d686c28258dbd53d58a99e4bbd9d250c288f585dc0df8f9b",
-  "solarmach.tests.test.test_solarmach_pfss": "ee9c8886e831b834c79da3a3078d1a9bb0845217b4c6217d48c7d4cbdb34d723"
+  "solarmach.tests.test.test_solarmach_plot[Carrington-numbers-True-270]": "340c9cd49b5b4b167bca92b832e693d1087c5b87ceedf1d52d00e0119c68b121",
+  "solarmach.tests.test.test_solarmach_plot[Stonyhurst-letters-False-0]": "802af17af20c79b80c7e35b8262b194de6053eb6188f2b3f494d991dafe09e01",
+  "solarmach.tests.test.test_solarmach_pfss": "3e1397b7e555862d47419969d2f762201e7d71d5cf79fff7cc8ac9a35f51b828"
 }

solarmach/tests/test.py

@@ -116,9 +116,10 @@ def test_solarmach_wrong_datetime_format():
 """
 
 
-@pytest.mark.mpl_image_compare(hash_library=Path(__file__).parent / 'figure_hashes_mpl_391.json', deterministic=True)
+@pytest.mark.parametrize("coord_sys, markers, fix_earth, long_offset", [('Carrington', 'numbers', True, 270), ('Stonyhurst', 'letters', False, 0)])
+# @pytest.mark.mpl_image_compare(hash_library=Path(__file__).parent / 'figure_hashes_mpl_391.json', deterministic=True)
 @pytest.mark.filterwarnings("ignore:FigureCanvasAgg is non-interactive, and thus cannot be shown:UserWarning:solarmach")
-def test_solarmach_plot():
+def test_solarmach_plot(coord_sys, markers, fix_earth, long_offset):
     body_list = ['STEREO-A']
     vsw_list = [400]
     date = '2021-10-28 15:15:00'
@@ -131,10 +132,10 @@ def test_solarmach_plot():
     long_sector_color='red'
     background_spirals=[6, 600]
 
-    sm = SolarMACH(date=date, body_list=body_list, vsw_list=vsw_list, reference_long=reference_long, reference_lat=reference_lat)
+    sm = SolarMACH(date=date, body_list=body_list, vsw_list=vsw_list, reference_long=reference_long, reference_lat=reference_lat, coord_sys=coord_sys)
     fig, ax = sm.plot(plot_spirals=True, plot_sun_body_line=True,
                       reference_vsw=reference_vsw, transparent=False,
-                      show_earth_centered_coord=False, markers='numbers',
+                      markers=markers, fix_earth=fix_earth,
                       long_sector=long_sector, long_sector_vsw=long_sector_vsw, long_sector_color=long_sector_color,
                       background_spirals=background_spirals, outfile=filename, return_plot_object=True)
     assert os.path.exists(os.getcwd()+os.sep+filename)