[issue34803] argparse int type does not accept scientific notation

[paul j3]

Change by paul j3 :


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resolution:  -> not a bug
stage:  -> resolved
status: open -> closed

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[issue34803] argparse int type does not accept scientific notation

[paul j3]

paul j3  added the comment:

The `type` parameter is normally a function (or more generally a callable).  
When given a string it should convert it as needed, or raise an error.  In your 
example that function is the stock, 'int()'.

Test `int('123')`, `int('1e3')` etc for yourself to see what it can handle.

If you want to convert '1e3' to an integer, write your own function that handle 
it.  Don't expect argparse or the stock int() to do it for you.

More commonly people use 'type=bool', expecting it convert 'True' or 'False' 
strings to boolean values.  But that's not what the bool() function does.

To reiterate, 'type' is a function, not a desired class.

Since this is not a bug, I think this should be closed.

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nosy: +paul.j3

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[issue34803] argparse int type does not accept scientific notation

[Karthikeyan Singaravelan]

Change by Karthikeyan Singaravelan :


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nosy: +xtreak

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[issue34803] argparse int type does not accept scientific notation

[Pablo Galindo Salgado]

Pablo Galindo Salgado  added the comment:

You can always do:

import argparse
foo = int(1e3) # Works: foo = 1000
parser = argparse.ArgumentParser()
parser.add_argument( "--foo", type=lambda x: int(float(x)))
parser.parse_args( ["--foo=1e3"] )

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[issue34803] argparse int type does not accept scientific notation

[Pablo Galindo Salgado]

Pablo Galindo Salgado  added the comment:

The conversion fails because is trying to convert a string, not a float:

>>> int("1e3")
*** ValueError: invalid literal for int() with base 10: '1e3'

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nosy: +pablogsal

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[issue34803] argparse int type does not accept scientific notation

[Jesse Hostetler]

Jesse Hostetler  added the comment:

I suppose desired behavior would be to accept the argument only if it can be 
converted to int without loss of information.

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[issue34803] argparse int type does not accept scientific notation

[Jesse Hostetler]

New submission from Jesse Hostetler :

The 'argparse' module gives a parse error for integer arguments written in 
scientific notation. I would expect this to work, since integers can be 
constructed from literals in scientific notation.

Example (also attached):

import argparse
foo = int(1e3) # Works: foo = 1000
parser = argparse.ArgumentParser()
parser.add_argument( "--foo", type=int )
parser.parse_args( ["--foo=1e3"] )
# error: argument --foo: invalid int value: '1e3'

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components: Library (Lib)
files: argparse-int-scientific.py
messages: 326409
nosy: jessehostetler
priority: normal
severity: normal
status: open
title: argparse int type does not accept scientific notation
type: enhancement
versions: Python 3.7
Added file: https://bugs.python.org/file47824/argparse-int-scientific.py

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