Issue with plotting vector fields

[bhvzchhn]

I am following the tutorial and I get the following error. I am using python 3.7.
For scalar fields, I do not have any issues.

---

IndexError Traceback (most recent call last)
in
1 grid_per = pde.CartesianGrid([[0, 4np.pi], [0, 2np.pi]], [128, 32], periodic=True)
2 vector_field = pde.VectorField.from_expression(grid_per, ['1', 'cos(x)'])
----> 3 vector_field.plot();

/usr/local/lib/python3.7/dist-packages/pde/tools/plotting.py in wrapper(title, filename, action, ax_style, fig_style, ax, *args, **kwargs)
285
286 # call the actual plotting function
--> 287 reference = wrapped(*args, ax=ax, **kwargs)
288
289 # finishing touches...

/usr/local/lib/python3.7/dist-packages/pde/fields/base.py in plot(self, kind, **kwargs)
1862 reference = self._plot_line(**kwargs)
1863 elif kind == "vector":
-> 1864 reference = self._plot_vector(**kwargs)
1865 else:
1866 raise ValueError(

/usr/local/lib/python3.7/dist-packages/pde/fields/base.py in _plot_vector(self, ax, method, transpose, max_points, **kwargs)
1740 # do the plotting using the chosen method
1741 if method == "quiver":
-> 1742 data = self.get_vector_data(transpose=transpose, max_points=max_points)
1743 element = ax.quiver(
1744 data["x"], data["y"], data["data_x"].T, data["data_y"].T, **kwargs

/usr/local/lib/python3.7/dist-packages/pde/fields/vectorial.py in get_vector_data(self, transpose, max_points, **kwargs)
638 data["data_y"] = np.take(data["data_y"], idx_i, axis=axis)
639 if axis == 0:
--> 640 data["y"] = data["y"][idx_i]
641 elif axis == 1:
642 data["x"] = data["x"][idx_i]

IndexError: index 34 is out of bounds for axis 0 with size 32

[david-zwicker]

Thanks for reporting this issue! It turned out there were several bugs in the function for plotting vector fields. I fixed these in the latest version on the master branch and these fixes will be included in the next release of py-pde.