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argparse/python - how to specify order of argument parsing?

+1 vote
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When using argparse, is there a way to specify in what order arguments get parsed? I am writing a script whose parameters can be modified in the following order:

Defaults -> config file -> command-line switches.

However, I want to give the option of specifying a config file using a command line switch as well, so logically, that file should be parsed before any other arguments are applied. However, it seems that parse_args() parses arguments in the order they're given, so if the config file switch is not given first, the config file will overwrite whatever was in the command-line switches, which should have higher priority.

posted Aug 31, 2013 by Abhay Kulkarni

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1 Answer

+1 vote

While I haven't come up with a good solution using argparse/optparse alone, I've found that it's easier (for processing) to specify the config file as an environment variable. So rather than doing

my_prog.py -c /path/to/config.ini arg1 arg2 ...

I just do

 MY_PROG_CONF=/path/to/config.ini my_prog.py arg1 arg2 ...

...at least on *nix systems; on Win32, it's

 c:temp> set MY_PROG_CONF=c:pathtoconfig.ini
 c:temp> python my_prog.py arg1 arg2 ...

Then you just intercept the config-file name from os.environ:

 config_file = os.environ.get("MY_PROG_CONF", default_ini_location)
answer Aug 31, 2013 by Sheetal Chauhan
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+2 votes

Iam on python 2.7 and linux .I need to know if we need to place the modules in a particular or it doesn't matter at all while writing the program.

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In the above example :

I am guessing may be the python modules like os , shlex etc come first and later the user defined modules like import plaftform.cluster etc

Sorry if my question sounds dump , I was running pep8 and don't see its bothered much about it

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+2 votes

How can I flatten just a specific sublist of each list in a list of lists?

So if I had this data

[ ['46295', 'Montauk', '3', '60', '85', ['19', '5', '1', '0 $277790.00']],
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How can I make it be

[ ['46295', 'Montauk', '3', '60', '85', '19', '5', '1', '0 $277790.00'],
 ['46295', 'Dark Eyes', '5', '59', '83', '6', '4', '1', '0 $105625.00'],
 ['46295', 'Machinegun Jubs', '6', '53', '77', '6', '2', '1', '1 $71685.00'],
 ['46295', 'Zara Bay', '1', '53', '77', '12', '2', '3', '3 $112645.00']]

Been looking around but most solutions just entirely flatten everything. This was popular on SO but yeah it flattens everything I want to be more selective

def flatten(lst):
 for elem in lst:
 if type(elem) in (tuple, list):
 for i in flatten(elem):
 yield i
 else:
 yield elem

What I am thinking is that if for each list the sublist should be at index 1, so

[0][1]
[1][1]
[2][1]

for item in list:
 item[1] - somehow flatten.

Any Idea or pointer?

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