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58 lines
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1.8 KiB
Markdown
58 lines
No EOL
1.8 KiB
Markdown
---
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aliases:
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- /blog/python-argpase/
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date: 2022-05-16 17:07:06-04:00
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draft: false
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math: false
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medium_enabled: true
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medium_post_id: 7d4c148bd2d0
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tags:
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- Python
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title: Python Argument Parser
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---
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*For a much better description of argument parsing in Python, please visit https://docs.python.org/3/library/argparse.html.*
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I'm creating this post because even though it's not too complicated, I keep forgetting how to do argument parsing in Python. I also tricked myself into thinking each time that I already wrote a blog post on this. Let's correct this once and for all and include a quick example!
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```python
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import argparse
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parser = argparse.ArgumentParser(description="Description to show in help")
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parser.add_argument("pos_arg1", type=str, help="Required positional argument")
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parser.add_argument("--flag1", type=str, help="Optional flag argument")
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parser.add_argument("--flag2", type=int, required=True, help="Required flag argument")
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parser.add_argument("--flag3", type=int, default=0, help="Optional flag argument \
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with default value of 0")
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args = vars(parser.parse_args())
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```
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Now if you call the program with no arguments you'll get the following message:
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```
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usage: testarg.py [-h] [--flag1 FLAG1] --flag2 FLAG2 pos_arg1
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testarg.py: error: the following arguments are required: pos_arg1, --flag2
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```
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This comes with a built in `-h` as well!
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```
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usage: testarg.py [-h] [--flag1 FLAG1] --flag2 FLAG2 pos_arg1
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Description to show in help
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positional arguments:
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pos_arg1 Required positional argument
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optional arguments:
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-h, --help show this help message and exit
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--flag1 FLAG1 Optional flag argument
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--flag2 FLAG2 Required flag argument
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```
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Within the code you can parse the argument names by accessing the `args` dictionary.
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```python
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pos_arg1 = args['pos_arg1']
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flag1 = args['flag1']
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flag2 = args['flag2']
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``` |