Refactoring of plotting and stencil plotting

- stencil plotting & transformation now in ps.stencil
- additional documentation & notebooks

pystencils_tests/test_finite_differences.py

 import sympy as sp
 import pystencils as ps
 from pystencils.astnodes import LoopOverCoordinate
-from pystencils.stencils import stencil_coefficients
 from pystencils.fd.spatial import fd_stencils_standard, fd_stencils_isotropic, discretize_spatial
 from pystencils.fd import diff
 
@@ -22,7 +21,7 @@ def test_spatial_2d_unit_sum():
     for term in terms:
         for scheme in schemes:
             discretized = discretize_spatial(term, dx=h, stencil=scheme)
-            _, coefficients = stencil_coefficients(discretized)
+            _, coefficients = ps.stencil.coefficients(discretized)
             assert sum(coefficients) == 0
 
 
@@ -38,7 +37,7 @@ def test_spatial_1d_unit_sum():
     for term in terms:
         for scheme in schemes:
             discretized = discretize_spatial(term, dx=h, stencil=scheme)
-            _, coefficients = stencil_coefficients(discretized)
+            _, coefficients = ps.stencil.coefficients(discretized)
             assert sum(coefficients) == 0
 
 

pystencils_tests/test_plot.py

+import os
+from tempfile import TemporaryDirectory
+import numpy as np
+import pystencils.plot as plt
+
+
+def example_scalar_field(t=0):
+    x, y = np.meshgrid(np.linspace(0, 2 * np.pi, 100), np.linspace(0, 2 * np.pi, 100))
+    z = np.cos(x + 0.1 * t) * np.sin(y + 0.1 * t) + 0.1 * x * y
+    return z
+
+
+def example_vector_field(t=0, shape=(40, 40)):
+    result = np.empty(shape + (2,))
+    x, y = np.meshgrid(np.linspace(0, 2 * np.pi, shape[0]), np.linspace(0, 2 * np.pi, shape[1]))
+    result[..., 0] = np.cos(x + 0.1 * t) * np.sin(y + 0.1 * t) + 0.01 * x * y
+    result[..., 1] = np.cos(0.001 * y)
+    return result
+
+
+def test_animation():
+    t = 0
+
+    def run_scalar():
+        nonlocal t
+        t += 1
+        return example_scalar_field(t)
+
+    def run_vec():
+        nonlocal t
+        t += 1
+        return example_vector_field(t)
+
+    plt.clf()
+    plt.cla()
+
+    with TemporaryDirectory() as tmp_dir:
+        ani = plt.vector_field_magnitude_animation(run_vec, interval=1, frames=2)
+        ani.save(os.path.join(tmp_dir, "animation1.avi"))
+
+        ani = plt.vector_field_animation(run_vec, interval=1, frames=2, rescale=True)
+        ani.save(os.path.join(tmp_dir, "animation2.avi"))
+
+        ani = plt.vector_field_animation(run_vec, interval=1, frames=2, rescale=False)
+        ani.save(os.path.join(tmp_dir, "animation3.avi"))
+
+        ani = plt.scalar_field_animation(run_scalar, interval=1, frames=2, rescale=True)
+        ani.save(os.path.join(tmp_dir, "animation4.avi"))
+
+        ani = plt.scalar_field_animation(run_scalar, interval=1, frames=2, rescale=False)
+        ani.save(os.path.join(tmp_dir, "animation5.avi"))
+
+        ani = plt.surface_plot_animation(run_scalar, frames=2)
+        ani.save(os.path.join(tmp_dir, "animation6.avi"))

pystencils_tests/test_stencils.py

+import pystencils as ps
+
+