(And to those taking the thread seriously: this is all in jest. We won't change the indexing base. The idea is so preposterous that the only kind of response possible is to laugh with it.)

--Guido

http://mail.python.org/pipermail/python-ideas/2011-September...

Few people seem to know that we have real and valid reasons for indexing from 0 instead of 1.

The first is so that the number of elements in the array/list/vector/collection is given by upper-lower.

The second is so that successive intervals re-use the same number, the upper bound of one becoming the lower bound of the next.

This is python we can have:

    L[:3], L[3:6], L[6:23], L[23:40], L[40:]

    L[start:end]

If you're talking about numbers from 13 onwards, it doesn't really make sense to talk about numbers greater than 12. More specifically, if you start counting from 0 then it feels (to me) more natural to include the lower bound.

If you talk about {5 .. 13} then it feels easier to say

    "From 5 up to (but not including) 13,"

    "From 5, er, sorry, no, from *6* up to and including 13."

http://www.paulgraham.com/taste.html

In the end it is all about convention, and what ends up making code cleaner, less error-prone, and more aesthetically pleasing. As I say, there are questions of taste and experience. Personally I find the Dijkstra/Python method for more consistent and pleasing than the alternatives.

It is often very inconvenient when mathematicians number from 1 instead of 0. A classic example is with Fourier matrices. Let w be a primitive nth root of unity. Then numbering as computer scientists, starting with 0, the formula is F(i,j) = w^(i j). But using the mathematician's convention, it is F(i,j) = w^((i-1)(j-1)). The same issue exists with all Vandermonde matrices.

"Because people count from one, not zero.

We do that in kindergarten, in music, when starting a race, when drawing up an agenda, everywhere. One, two, three, etc have their counterparts in every known language on earth.

Zero, on the other hand, is an advanced concept. Humanity could prove that sqrt(2) is not a rational number centuries before anybody thought that a symbol for zero might be useful.

A harder question would be "why do arrays in some other languages count from zero not one?" The answer for C is a good one: "so that * (A+k) and A[k] mean the same". For Python, the answer seems to be "because it's that way in C"."

And:

"Currently, many languages are 0-based due to influence from C. Ironically, none of them share the reason that made C 0-based (where a[e] means * (a+e))."

(EDIT: I had to add spaces after the stars to prevent HN from italicizing a huge block of text.

  G = ground = 0;
  A[G], A[1], A[2], ...

This is confusing for some people (unfamiliar with the situation), who need to go to a number in the basement but consistently turn up two floors higher.

Music uses both systems.

A chromatic approach uses a 0-indexed system while the classical diatonic scales and intervals are indexed at 1. A perfect 5th is a chromatic interval of 7 semitones.

1-do(0) 2-re(2) 3-me(4) 4-fa(5) 5-sol(7) 6-la(9) 7-ti(11)

The question is whether it's more useful to count the notes that appear and label them with numbers, or to measure the difference between them.

For example, imagine I want to fake an nm 2d matrix M with an array A, with nm elements

Then with 0-indexing, M[i][j] is stored at A[im+j]. With 1-indexing, M[i][j] is stored at A[(i-1)m+j].

  $[ = 1;

The older I get the more Larry Wall strikes me as like a really well intentioned hippy type; when in God's green earth has it been a good idea to allow a five character statement change the truth values of nearly every for loop in a body of code?

Perl always claimed it gave you enough rope to hang yourself, but this goes far, far beyond that. This is like building the scaffolding and marking it like "Young developers, play here! Ropes are fun!"

2) As of Perl 5+ it's evaluated at compile-time rather than run-time, which is not as bad as if you could flip back and forth at runtime. Though you can use 'local' to lexically scope its effects -- hilarity ensues as you hand off said code to someone else for maintenance.

3) It's from a different era. As per the docs:

    Default is 0, but you could theoretically set
    it to 1 to make Perl behave more like awk (or
    Fortran)

[ Though the core of SciPy/NumPy is notably written in Fortran. Not quite as dead as some would have you believe. ]

How about this in C(and thousand others): #define if while

I am pretty sure I can find something to horrify you in almost any language.

    >>> import sys
    >>> import ctypes
    >>> pyint_p = ctypes.POINTER(ctypes.c_byte*sys.getsizeof(5))
    >>> five = ctypes.cast(id(5), pyint_p)
    >>> 2 + 2 == 5
    False
    >>> five.contents[five.contents[:].index(5)] = 4
    >>> 2 + 2 == 5
    True

Here's a small snippet that let you add methods to built-ins:

  def inject(cls, wrapper=lambda x: x, name=None):
      def _builtin_hack(name):
          import ctypes as c
  
          _get_dict = c.pythonapi._PyObject_GetDictPtr
          _get_dict.restype = c.POINTER(c.py_object)
          _get_dict.argtypes = [c.py_object]
  
          return _get_dict(name).contents.value
  
      def wrap(method):
          name_ = name or method.func_name
          method = wrapper(method)
  
          try:
              setattr(cls, name_, method)
          except:
              _builtin_hack(cls)[name_] = method
  
      return wrap  


    @inject(dict)
    def extend(self, new_dict):
        return dict(self, **new_dict)

    print {'a':2}.extend({'b':3})

I think I discovered the hack when I found out about the id() function, and hex(id(5)) looked suspiciously like a pointer value. (And http://docs.python.org/library/functions.html#id confirms.) http://docs.python.org/library/ctypes.html has usually been pretty useful. Apart from that, just play.

    $ python -c "import ctypes; ctypes.memset(0, 0, 42)"
    Segmentation fault

  #define break continue

  irb(main):001:0> if 0
  irb(main):002:1> print "True!"
  irb(main):003:1> end
  True!=> nil

(not to post something useless, but I'm literally speechless going back and forth between "that's so awesome" and "that's so dumb" in my head for so many different reasons)

(and at how short and quick Guido's response was, as if it was such an easy decision to make.)

edit: also found this later in the thread to confirm the humor behind everything: http://mail.python.org/pipermail/python-ideas/2011-September...

Loved this response http://mail.python.org/pipermail/python-ideas/2011-September...