is_nonstr_iter recognize 0-D numpy array as iterable #4001
Description
As shown below, a 0-D numpy array is recognized as iterable by the is_nonstr_iter function, but actually we can't loop over it.
In [1]: import numpy as np
In [2]: x = np.array(40)
In [3]: x.ndim
Out[3]: 0
In [4]: from pygmt.helpers import is_nonstr_iter
In [5]: is_nonstr_iter(x)
Out[5]: True
In [6]: from collections.abc import Iterable, Iterator
In [7]: isinstance(x, Iterable)
Out[7]: True
In [8]: [i for i in x]
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
Cell In[9], line 1
----> 1 [i for i in x]
TypeError: iteration over a 0-d array
In [9]: "/".join(x)
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
Cell In[10], line 1
----> 1 "/".join(x)
TypeError: can only join an iterableSo, a 0-D numpy array is iterable (has the __iter__ method) but is not an iterator (doens't have the __next__ method).
In [8]: isinstance(x, Iterator)
Out[8]: False
Because we usually need to loop over an iterable or join an iterable, perhaps we should use isinstance(x, Iterator) rather than isinstance(x, Iterable)?
Edit: isinstance([2, 3, 4], Iterator) returns False, so it doens't work.