Python> Run with run-time arguments> Use import argparse

Operating environment

Xeon E5-2620 v4 (8 cores) x 2
32GB RAM
CentOS 6.8 (64bit)
openmpi-1.8.x86_64 and its-devel
mpich.x86_64 3.1-5.el6 and its-devel
gcc version 4.4.7 (And gfortran)
NCAR Command Language Version 6.3.0
WRF v3.7.Use 1.
Python 2.6.6 (r266:84292, Aug 18 2016, 15:13:37) 
Python 3.6.0 on virtualenv

I want to execute by specifying the runtime argument in the Python script being implemented.

Reference http://qiita.com/munkhbat1900/items/d7f9b11fb0965085964e Reference http://qiita.com/petitviolet/items/b8ed39dd6b0a0545dd36

v0.1 > AttributeError: 'Namespace' object has no attribute 't'

The following implementation was made with reference to the above two.

test_python_170323i.py

import argparse

parser = argparse.ArgumentParser(description = "do something")

parser.add_argument(
	'-t',
	'--timeIndex',
	type = int,
	help = 'time index for netCDF file',
	required = True)

cmd_args = parser.parse_args()

print(cmd_args.t)

$ python test_python_170323i.py -t 314
Traceback (most recent call last):
  File "test_python_170323i.py", line 14, in <module>
    print(cmd_args.t)
AttributeError: 'Namespace' object has no attribute 't'

There is no attribute called t.

v0.2> Success

test_python_170323i.py

import argparse

parser = argparse.ArgumentParser(description = "do something")

parser.add_argument(
	'-t',
	'--timeIndex',
	type = int,
	help = 'time index for netCDF file',
	required = True)

cmd_args = parser.parse_args()

print(cmd_args.timeIndex)

result

$ python test_python_170323i.py -t 314
314

When --timeIndex is specified, it seems that .timeIndex is used instead of .t when reading.

https://docs.python.jp/3/library/argparse.html It seems to be related.

v0.3> Specify attribute name

It seems that you can specify the attribute name by specifying dest.

https://docs.python.jp/3/library/argparse.html 16.4.1.2. Add arguments

The accumulate attribute is specified from the command line if --sum is specified

import argparse

parser = argparse.ArgumentParser(description = "do something")

parser.add_argument(
	'-t',
	'--timeIndex',
	dest='time_index',
	type=int,
	help='time index for netCDF file',
	required=True)

cmd_args = parser.parse_args()

print(cmd_args.time_index)

Remarks

$ python calc_latlon_avg_std_170323.py --timeIndex -20
total: 3477.89
avg_lat: 40.480
avg_lon: 116.246
std_lat: 0.137
std_lon: 0.103

$ python calc_latlon_avg_std_170323.py --timeIndex 4
total: 3477.89
avg_lat: 40.480
avg_lon: 116.246
std_lat: 0.137
std_lon: 0.103

-20 is accepted when timeIndex is specified. The value is 24, which is wraparound, and the result is the same as when 4 is specified. (The timeIndex is actually specified by [0..23]).