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Re: Trees

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On Tuesday, January 20, 2015 at 11:38:27 AM UTC+5:30, Terry Reedy wrote:
> On 1/19/2015 5:06 PM, Zachary Gilmartin wrote:
> > Why aren't there trees in the python standard library?
> 
> Sequences nested withing sequences can be regarded as trees, and Python 
> has these.  I regard Lisp as a tree processing languages, as it must be 
> to manipulate, for example, code with nested structures.

Yeah python has trees alright.

Heres' some simple tree-code

from enum import Enum
class TreeTag(Enum):
    I = 0  # An internal node
    L = 1  # A leaf node
    def __repr__(self):  return self.name
    
I = TreeTag.I
L = TreeTag.L


def dfs(t):
    if t[0] == L:
        return [t[1]]
    else:
        return [t[1]] + dfs(t[2]) + dfs(t[3])

# Converting to generators is trivial
=====================

# Example tree
# From http://www-math.ucdenver.edu/~wcherowi/courses/m4408/gtln8.html

t1 = [L, 1]
t4 = [I, 4, [L, 3],[L,5]]
t2 = [I, 2, t1, t4]
t8 = [I, 8, [L, 7], [L, 9]]

# Top level tree
t = [I, 6, t2, t8]


======================
An REPL session

>>> t
[I, 6, [I, 2, [L, 1], [I, 4, [L, 3], [L, 5]]], [I, 8, [L, 7], [L, 9]]]
>>> dfs(t)
[6, 2, 1, 4, 3, 5, 8, 7, 9]
>>> t8
[I, 8, [L, 7], [L, 9]]
>>> dfs(t8)
[8, 7, 9]
>>> 

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Re: Trees Terry Reedy <tjreedy@udel.edu> - 2015-01-20 01:08 -0500
  Re: Trees Marko Rauhamaa <marko@pacujo.net> - 2015-01-20 11:45 +0200
    Re: Trees Paul Rubin <no.email@nospam.invalid> - 2015-01-20 10:14 -0800
      Re: Trees Marko Rauhamaa <marko@pacujo.net> - 2015-01-20 22:26 +0200
    Re: Trees Stephen Hansen <me+python@ixokai.io> - 2015-01-20 23:56 -0800
      Re: Trees Marko Rauhamaa <marko@pacujo.net> - 2015-01-21 10:35 +0200
      Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-21 04:09 -0800
        Re: Trees Chris Angelico <rosuav@gmail.com> - 2015-01-21 23:35 +1100
          Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-21 07:24 -0800
        Re: Trees Tim Chase <python.list@tim.thechases.com> - 2015-01-21 06:55 -0600
        Re: Trees Chris Angelico <rosuav@gmail.com> - 2015-01-22 00:01 +1100
        Re: Trees Tim Chase <python.list@tim.thechases.com> - 2015-01-21 08:26 -0600
        Re: Trees Chris Angelico <rosuav@gmail.com> - 2015-01-22 01:31 +1100
        Re: Trees Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-22 01:47 +1100
          Re: Trees Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-21 09:15 -0700
          Re: Trees Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-21 10:27 -0700
  Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-20 05:33 -0800
    Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-20 05:51 -0800
    Re: Trees Marko Rauhamaa <marko@pacujo.net> - 2015-01-20 16:15 +0200
      Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-20 06:35 -0800
    Re: Trees Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-20 10:19 -0700
      Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-20 10:15 -0800
        Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-20 10:35 -0800
    Re: Trees Mario <marfig@gmail.com> - 2015-01-20 22:47 +0100
      Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-20 17:23 -0800
        Re: Trees Paul Rubin <no.email@nospam.invalid> - 2015-01-20 17:49 -0800
          Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-20 18:03 -0800
            Re: Trees Paul Rubin <no.email@nospam.invalid> - 2015-01-21 14:27 -0800
              Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-21 21:17 -0800
        Re: Trees Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-21 15:54 -0700
          Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-21 21:20 -0800
            Re: Trees Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-22 00:01 -0700
            Re: Trees Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-21 23:56 -0700
          Re: Trees Paul Rubin <no.email@nospam.invalid> - 2015-01-21 23:16 -0800
            Re: Trees Rustom Mody <rustompmody@gmail.com> - 2015-01-22 08:54 -0800
      Re: Trees Terry Reedy <tjreedy@udel.edu> - 2015-01-20 21:19 -0500
        Re: Trees Mario Figueiredo <marfig@gmail.com> - 2015-01-21 14:05 +0000

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