arg less main() for pip install -e

[yunjunz]

It seems when installing mintpy using pip install -e MintPy, the command-line options are not working:

(insar) kyushu:~/data/offset4motion/SaltonSeaSenDT173/merged/test/20191220_20201220>$ view.py off3_snr.bip -v 0 100 --flip-lr
Traceback (most recent call last):
  File "/home/zyunjun/tools/miniconda3/envs/insar/bin/view.py", line 33, in <module>
    sys.exit(load_entry_point('mintpy', 'console_scripts', 'view.py')())
  File "/home/zyunjun/tools/MintPy/mintpy/view.py", line 1663, in main
    obj.configure()
  File "/home/zyunjun/tools/MintPy/mintpy/view.py", line 1538, in configure
    inps = cmd_line_parse(self.iargs)
  File "/home/zyunjun/tools/MintPy/mintpy/view.py", line 175, in cmd_line_parse
    geo_opt_names = list(set(geo_opt_names) & set(iargs))
TypeError: 'NoneType' object is not iterable

The solution could be using the sys.argv all the time as suggested in insarlab#652. view.py has the most complicated usage of iargs. If the following 3 scenarios works, then it should be safe to translate the rest of mintpy to arg less main() style:

1. view.py velocity.h5 -v 0 3 --flip-lr # command line in terminal
2. view.main('velocity.h5 -v 0 3 --flip-lr'.split()) # main function call in python
3. view and tsview interactive jupyter notebook: https://github.com/insarlab/MintPy-tutorial/tree/main/visualization

[jhkennedy]

@yunjunz this issues is caused by trying to convert iargs to s set when it's value is None here:
https://github.com/yunjunz/MintPy/blob/main/mintpy/view.py#L175

>>> set(None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'NoneType' object is not iterable

You'll likewise have problems trying to join(None) here:
https://github.com/yunjunz/MintPy/blob/main/mintpy/view.py#L185

>>> ' '.join(None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can only join an iterable

In the old install, you set iargs=sys.argv[1:]:
https://github.com/yunjunz/MintPy/blob/main/mintpy/view.py#L1677

So if you wanted to have the old behavior, you could do the same with a:

if iargs is None:
    iargs = sys.argv[1:]

This will have issues, however, where sys.argv is related to how the interpreter was launched. So you'd probably actually just want:

if iargs is None:
    iargs = []

which will look like the old case where the script was invoked without any arguments.

---

In general, I'd caution against doing operations against sys.argv and instead would suggest the logic would be better done looking at your parsed args (inps) as argparse handles a lot of gotchas with sys.argv.
https://github.com/yunjunz/MintPy/blob/main/mintpy/view.py#L141

[yunjunz]

Thank you @jhkennedy for the diagnose. The following modification seems to work in all three scenarios for versions installed via pip or path setup. I have issued a PR for it.

# save argv (to check the manually specified arguments)
# use iargs        for python call
# use sys.argv[1:] for command line call
inps.argv = iargs if iargs else sys.argv[1:]