5 ms·

So you think you know what a number is

64 points by DamonHD 10y ago

badosu 10y ago
Expecting to see some foundational mathematical logic content, was disappointed.
- DamonHD 10y ago
  Terry, is that you? B^>
- manaskarekar 10y ago
  I was expecting GEB references. https://en.m.wikipedia.org/wiki/Gödel,_Escher,_Bach https://en.m.wikipedia.org/wiki/Gödel,_Escher,_Bach
  - DamonHD 10y ago
    Having actually done a little number theoretical stuff back in the day, I see what you mean, but prosaically this was astonishing enough for me to make the link worth posting: Decimal characters include digit characters, and all characters that can be used to form decimal-radix numbers, e.g. U+0660, ARABIC-INDIC DIGIT ZERO. Rigid designators vs definite descriptions for numerals, anyone?
  - badosu 10y ago
    This is a pretty good article that could satisfy the headline: https://johncarlosbaez.wordpress.com/2016/06/29/large-countable-ordinals-part-1/ https://johncarlosbaez.wordpress.com/2016/06/29/large-counta...
- Maken 10y ago
  Too bad, it's your old friend Unicode.
  - DoofusOfDeath 10y ago
    No worries, I'm sure the next version of Unicode will have a single glyph that provides a complete introduction to the topic.
    - stcredzero 10y ago
      We need to extend Unicode to account for quantum computing and qubits. It needs to evolve into Qunicode. Text with this feature baked in could be called Quneiform. It should be stored on light-reflecting crystals that are manufactured using kilns.
      - deleted 10y ago
        [deleted]
      - badosu 10y ago
        It's turtles all the way!
      - clock_tower 10y ago
        You should join the Unicode Consortium; I'm pretty sure you'd fit right in. :)
  - jdmichal 10y ago
    I had an encoding problem once, so I used Unicode. Now I have ۲۶۷۹ problems.
- Sniffnoy 10y ago
  Should perhaps be called "So you think you know what a numeral is". Still interesting though.
lacker 10y ago
It's neat how that link lets you run Python interactively in the browser, with https://repl.it/site/languages/python3 https://repl.it/site/languages/python3 . Normally that is just a JavaScript thing.
ianbertolacci 10y ago
>>> int("۲۶۷۹") 2679 Thats pretty cool.
- Tistron 10y ago
  Indeed. Seems to be a thing of python 3. $ ruby -v ruby 2.2.6p396 (2016-11-15 revision 56800) [x86_64-linux-gnu] $ ruby -e "puts \"۲۶۷۹\".to_i" 0 $ python2.7 -c "print(int(\"۲۶۷۹\"))" Traceback (most recent call last): File "<string>", line 1, in <module> ValueError: invalid literal for int() with base 10: '\xdb\xb2\xdb\xb6\xdb\xb7\xdb\xb9' $ python3.5 -c "print(int(\"۲۶۷۹\"))" 2679 $ node -v v6.9.1 $ node -p "parseInt(\"۲۶۷۹\")" NaN
  - plus 10y ago
    It works in Python 2, you just have to ensure that your string is unicode. I can't get it to work directly from the command line for some reason, but if you open an interactive Python session it works: Python 2.7.12 (default, Dec 14 2016, 13:32:53) [GCC 4.9.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> print(int(u'۲۶۷۹')) 2679
    - Tistron 10y ago
      Hmm, interesting. What's up with the terminal here? The shell is doing something to the text. $ python2.7 -c "print(int(u'۲۶۷۹'))" Traceback (most recent call last): File "<string>", line 1, in <module> ValueError: invalid literal for int() with base 10: '\xdb\xb2\xdb\xb6\xdb\xb7\xdb\xb9' $ python2.7 Python 2.7.13 (default, Jan 03 2017, 17:41:54) [GCC] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> print(int(u'۲۶۷۹')) 2679 Looking at what the string is: $ python2.7 -c "print(list(u'۲۶۷۹'))" [u'\xdb', u'\xb2', u'\xdb', u'\xb6', u'\xdb', u'\xb7', u'\xdb', u'\xb9'] $ python2.7 Python 2.7.13 (default, Jan 03 2017, 17:41:54) [GCC] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> print(list(u'۲۶۷۹')) [u'\u06f2', u'\u06f6', u'\u06f7', u'\u06f9']
Veedrac 10y ago
Note that Python has str.isdecimal, str.isdigit and str.isnumeric. isdecimal isdigit isnumeric 12345 True True True ១2߃໔5 True True True ①²³🄅₅ False True True ⑩⒓ False False True Five False False False Use isdecimal if you want to call `int` (though it's EAFTP).
- detaro 10y ago
  Don't forget to special case negative numbers though.
cperciva 10y ago
Speaking of tools having trouble recognizing things, one of the more common "bug reports" I get is that the Tarsnap website is disclosing user email addresses -- specifically, "me@example.com" -- and paths -- specifically, the paths /home/auser and /home/anotheruser.
Grue3 10y ago
int("一万三千二百六十九") Traceback (most recent call last): File "python", line 1, in <module> ValueError: invalid literal for int() with base 10: '一万三千二百六十九' int("一三二六九") Traceback (most recent call last): File "python", line 1, in <module> ValueError: invalid literal for int() with base 10: '一三二六九' Well, that was disappointing. For the record, my site http://ichi.moe/ http://ichi.moe/ can handle both (and Arabic numerals too).
- Navarr 10y ago
  Speaking of Japanese, I previously wrote some pretty basic code for translating arabic to/from Japanese numerals: https://github.com/navarr/JapaneseNumerals/blob/master/JapaneseNumerals.js https://github.com/navarr/JapaneseNumerals/blob/master/Japan...
- acdha 10y ago
  That actually came up in the comments (http://chris.improbable.org/2014/8/25/adventures-in-unicode-digits/#comment-3279339258 http://chris.improbable.org/2014/8/25/adventures-in-unicode-...) Apparently the Unicode consortium chose to exclude those characters because they weren't encoded in a contiguous sequence so they're defined as Numeric_Type=Digit rather than Numeric_Type=Decimal. They've apparently realized that this is not helpful but chose to apply the updated policy only to new ranges.
- inimino 10y ago
  But those are the names of numbers, like "one", and not numerals. "one two three" would be the English equivalent.
phyzome 10y ago
This applies in Java as well, for instance Integer.parseInt and Character.isDigit. Between Java and Python, you can get all sorts of numeric characters through a sizable percentage of web applications. I haven't yet found a security vulnerability based in this, but I keep checking. :-)
- acdha 10y ago
  Also .Net: https://blogs.msdn.microsoft.com/oldnewthing/20040309-00/?p=40333 https://blogs.msdn.microsoft.com/oldnewthing/20040309-00/?p=... … and, yes, that was definitely something I tried to find when I first noticed it.
soVeryTired 10y ago
A partition of the rationals into sets U and V such that every u in U is less than every v in V?
gumby 10y ago
At least AFAIK all the non-CJKV scripts (except perhaps Mongolian?) use right-to-left decimal characters with 0. So you should be able to "transliterate" (transnumerate) ۲۶۷۹ to 2979 with a simple look up table and no R-L confusion. In fact ۲9۷9 should be the same.

64 points by DamonHD 10y ago

badosu 10y ago

Expecting to see some foundational mathematical logic content, was disappointed.

DamonHD 10y ago
Terry, is that you? B^>
manaskarekar 10y ago
I was expecting GEB references. https://en.m.wikipedia.org/wiki/Gödel,_Escher,_Bach https://en.m.wikipedia.org/wiki/Gödel,_Escher,_Bach
- DamonHD 10y ago
  Having actually done a little number theoretical stuff back in the day, I see what you mean, but prosaically this was astonishing enough for me to make the link worth posting: Decimal characters include digit characters, and all characters that can be used to form decimal-radix numbers, e.g. U+0660, ARABIC-INDIC DIGIT ZERO. Rigid designators vs definite descriptions for numerals, anyone?
- badosu 10y ago
  This is a pretty good article that could satisfy the headline: https://johncarlosbaez.wordpress.com/2016/06/29/large-countable-ordinals-part-1/ https://johncarlosbaez.wordpress.com/2016/06/29/large-counta...
Maken 10y ago
Too bad, it's your old friend Unicode.
- DoofusOfDeath 10y ago
  No worries, I'm sure the next version of Unicode will have a single glyph that provides a complete introduction to the topic.
  - stcredzero 10y ago
    We need to extend Unicode to account for quantum computing and qubits. It needs to evolve into Qunicode. Text with this feature baked in could be called Quneiform. It should be stored on light-reflecting crystals that are manufactured using kilns.
    - deleted 10y ago
      [deleted]
    - badosu 10y ago
      It's turtles all the way!
    - clock_tower 10y ago
      You should join the Unicode Consortium; I'm pretty sure you'd fit right in. :)
- jdmichal 10y ago
  I had an encoding problem once, so I used Unicode. Now I have ۲۶۷۹ problems.
Sniffnoy 10y ago
Should perhaps be called "So you think you know what a numeral is". Still interesting though.

lacker 10y ago

It's neat how that link lets you run Python interactively in the browser, with https://repl.it/site/languages/python3 https://repl.it/site/languages/python3 . Normally that is just a JavaScript thing.

ianbertolacci 10y ago

>>> int("۲۶۷۹") 2679 Thats pretty cool.

Tistron 10y ago
Indeed. Seems to be a thing of python 3. $ ruby -v ruby 2.2.6p396 (2016-11-15 revision 56800) [x86_64-linux-gnu] $ ruby -e "puts \"۲۶۷۹\".to_i" 0 $ python2.7 -c "print(int(\"۲۶۷۹\"))" Traceback (most recent call last): File "<string>", line 1, in <module> ValueError: invalid literal for int() with base 10: '\xdb\xb2\xdb\xb6\xdb\xb7\xdb\xb9' $ python3.5 -c "print(int(\"۲۶۷۹\"))" 2679 $ node -v v6.9.1 $ node -p "parseInt(\"۲۶۷۹\")" NaN
- plus 10y ago
  It works in Python 2, you just have to ensure that your string is unicode. I can't get it to work directly from the command line for some reason, but if you open an interactive Python session it works: Python 2.7.12 (default, Dec 14 2016, 13:32:53) [GCC 4.9.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> print(int(u'۲۶۷۹')) 2679
  - Tistron 10y ago
    Hmm, interesting. What's up with the terminal here? The shell is doing something to the text. $ python2.7 -c "print(int(u'۲۶۷۹'))" Traceback (most recent call last): File "<string>", line 1, in <module> ValueError: invalid literal for int() with base 10: '\xdb\xb2\xdb\xb6\xdb\xb7\xdb\xb9' $ python2.7 Python 2.7.13 (default, Jan 03 2017, 17:41:54) [GCC] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> print(int(u'۲۶۷۹')) 2679 Looking at what the string is: $ python2.7 -c "print(list(u'۲۶۷۹'))" [u'\xdb', u'\xb2', u'\xdb', u'\xb6', u'\xdb', u'\xb7', u'\xdb', u'\xb9'] $ python2.7 Python 2.7.13 (default, Jan 03 2017, 17:41:54) [GCC] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> print(list(u'۲۶۷۹')) [u'\u06f2', u'\u06f6', u'\u06f7', u'\u06f9']

Veedrac 10y ago

Note that Python has str.isdecimal, str.isdigit and str.isnumeric. isdecimal isdigit isnumeric 12345 True True True ១2߃໔5 True True True ①²³🄅₅ False True True ⑩⒓ False False True Five False False False Use isdecimal if you want to call `int` (though it's EAFTP).

detaro 10y ago
Don't forget to special case negative numbers though.

cperciva 10y ago

Speaking of tools having trouble recognizing things, one of the more common "bug reports" I get is that the Tarsnap website is disclosing user email addresses -- specifically, "me@example.com" -- and paths -- specifically, the paths /home/auser and /home/anotheruser.

Grue3 10y ago

int("一万三千二百六十九") Traceback (most recent call last): File "python", line 1, in <module> ValueError: invalid literal for int() with base 10: '一万三千二百六十九' int("一三二六九") Traceback (most recent call last): File "python", line 1, in <module> ValueError: invalid literal for int() with base 10: '一三二六九' Well, that was disappointing. For the record, my site http://ichi.moe/ http://ichi.moe/ can handle both (and Arabic numerals too).

Navarr 10y ago
Speaking of Japanese, I previously wrote some pretty basic code for translating arabic to/from Japanese numerals: https://github.com/navarr/JapaneseNumerals/blob/master/JapaneseNumerals.js https://github.com/navarr/JapaneseNumerals/blob/master/Japan...
acdha 10y ago
That actually came up in the comments (http://chris.improbable.org/2014/8/25/adventures-in-unicode-digits/#comment-3279339258 http://chris.improbable.org/2014/8/25/adventures-in-unicode-...) Apparently the Unicode consortium chose to exclude those characters because they weren't encoded in a contiguous sequence so they're defined as Numeric_Type=Digit rather than Numeric_Type=Decimal. They've apparently realized that this is not helpful but chose to apply the updated policy only to new ranges.
inimino 10y ago
But those are the names of numbers, like "one", and not numerals. "one two three" would be the English equivalent.

phyzome 10y ago

This applies in Java as well, for instance Integer.parseInt and Character.isDigit. Between Java and Python, you can get all sorts of numeric characters through a sizable percentage of web applications. I haven't yet found a security vulnerability based in this, but I keep checking. :-)

acdha 10y ago
Also .Net: https://blogs.msdn.microsoft.com/oldnewthing/20040309-00/?p=40333 https://blogs.msdn.microsoft.com/oldnewthing/20040309-00/?p=... … and, yes, that was definitely something I tried to find when I first noticed it.

soVeryTired 10y ago

A partition of the rationals into sets U and V such that every u in U is less than every v in V?

gumby 10y ago

At least AFAIK all the non-CJKV scripts (except perhaps Mongolian?) use right-to-left decimal characters with 0. So you should be able to "transliterate" (transnumerate) ۲۶۷۹ to 2979 with a simple look up table and no R-L confusion. In fact ۲9۷9 should be the same.