Generate labels for a multi-level outline

[python]

I need to generate multi-level incrementing labels for an
outline/hierarchy where the string for each level of a label is based on
an incrementing sequence like 1, 2, 3 or A, B, C, or even I, II, III.
For simplicity, assume that each level's label segment is separated by a
period (".").

I will pass an integer level (1 ... N) to this function/object so that
level specific counters get reset when the level changes.

I will use this function/object to generate output like:

Label Level
I. 1
I.A. 2
I.B. 2
I.C. 2
I.D. 2
I.D.1. 3
I.D.2. 3
I.D.3. 3
I.E. 2
II. 1

Is there a pre-built class for generating label sequences like this?
(I'm not sure what I would use as search terms to google for such a
class).

While this sounds like a simple/fun class to write, I think it could
quickly get complicated when one factors in parsing rules for each
level's label type, separators, and error checking. If there's an
existing, road tested class (with unit tests) that does this, I would
rather avoid re-inventing/re-testing the wheel.

Thanks,
Malcolm

[castironpi]

On May 6, 4:43*pm, [e-mail] wrote:

I need to generate multi-level incrementing labels for an
outline/hierarchy where the string for each level of a label is based on
an incrementing sequence like 1, 2, 3 or A, B, C, or even I, II, III.
For simplicity, assume that each level's label segment is separated by a
period (".").

I will pass an integer level (1 ... N) to this function/object so that
level specific counters get reset when the level changes.

I will use this function/object to generate output like:

Label * * Level
I. * * * *1
I.A. * * *2
I.B. * * *2
I.C. * * *2
I.D. * * *2
I.D.1. * *3
I.D.2. * *3
I.D.3. * *3
I.E. * * *2
II. * * * 1

Is there a pre-built class for generating label sequences like this?
(I'm not sure what I would use as search terms to google for such a
class).

While this sounds like a simple/fun class to write, I think it could
quickly get complicated when one factors in parsing rules for each
level's label type, separators, and error checking. If there's an
existing, road tested class (with unit tests) that does this, I would
rather avoid re-inventing/re-testing the wheel.

Thanks,
Malcolm

You've inquired about syntax here.

(simulated)

>>a.next( )

I.

>>a.throw( in )

I.A.

>>a.next( )

I.B.

>>a.next( )

I.C.

>>a.throw( out )

II.

I will implement the object (the term is "generator"), but you have
to count on two things: I can, and I'll check the newsgroup (i.e. bank
on the spare time of others). You're invited to reply with any and
all interest. Personally, the offer expires, but I'm not the only one
with the skill. (Stay tuned.)

(The trick to generators is "dis"inventing wheels.)

Is the formulation proposed satisfactory to you?

Would you prefer to yield a sequence of marks, as a further option, as
follows? (As opposed to the rejoined string.)

(simulated)

>>a.next( )

( "I", )

>>a.throw( in )

( "I", "A" )

>>a.next( )

( "I", "B" )

>>a.next( )

( "I", "C" )

>>a.throw( out )

( "II", )

At this point in conception, my proposal has -not- met your criterion
of:

I will pass an integer level (1 ... N) to this function/object so that
level specific counters get reset when the level changes.

but does proceed stepwise through my sequence.

(Further I am interested in other means of display of the information
you're presenting in the outline; feel free to brainstorm on this
group.)

Library: Python allows you to join sequences of strings simply:

>>".".join( ( "I", "A", "1", "iii" ) )

'I.A.1.iii'

But customization could make the return a multi-liner. Yes it's free,
what you've asked.

The implementation is subject to taste in one of two ways, whether
you're holding a mutable sequence of generators (per se), or just one,
but for beggars can't be choosers, the free code only comes with one.
If you will want to "go back and insert", generators are the -wrong-
solution (prop check).

[castironpi]

'''
On May 6, 4:43 pm, [e-mail] honoring:

>>a.next( )

( "I", )

>>a.throw( up )

( "I", "A" )

>>a.next( )

( "I", "B" )

>>a.next( )

( "I", "C" )

>>a.throw( down )

( "II", )
'''

#funny declaration
class up( Exception ): pass
class down( Exception ): pass

def outline( ):
stack= [ 1 ]
while 1:
try:
yield stack
stack[ -1 ]+= 1
except up:
stack.append( 1 )
except down:
stack.pop( -1 )
stack[ -1 ]+= 1

a= outline( )
print a.next( )
print a.throw( up )
print a.next( )
print a.next( )
print a.throw( down )
print a.throw( up )
print a.throw( up )
print a.next( )
print a.next( )
print a.throw( down )

##output:

[1]
[1, 1]
[1, 2]
[1, 3]
[2]
[2, 1]
[2, 1, 1]
[2, 1, 2]
[2, 1, 3]
[2, 2]

##

cf.

formatter.NullFormatter.format_counter
formatter.NullFormatter.format_letter
formatter.NullFormatter.format_roman

[castironpi]

On May 7, 9:07*am, [e-mail] wrote:

'''
On May 6, 4:43 pm, [e-mail] honoring:

>a.next( )

( "I", )

>a.throw( up )

( "I", "A" )

>a.next( )

( "I", "B" )

>a.next( )

( "I", "C" )

>a.throw( down )

( "II", )
'''

#funny declaration
class up( Exception ): pass
class down( Exception ): pass

def outline( ):
* * stack= [ 1 ]
* * while 1:
* * * * try:
* * * * * * yield stack
* * * * * * stack[ -1 ]+= 1
* * * * except up:
* * * * * * stack.append( 1 )
* * * * except down:
* * * * * * stack.pop( -1 )
* * * * * * stack[ -1 ]+= 1

a= outline( )
print a.next( )
print a.throw( up )
print a.next( )
print a.next( )
print a.throw( down )
print a.throw( up )
print a.throw( up )
print a.next( )
print a.next( )
print a.throw( down )

##output:

[1]
[1, 1]
[1, 2]
[1, 3]
[2]
[2, 1]
[2, 1, 1]
[2, 1, 2]
[2, 1, 3]
[2, 2]

##

cf.

formatter.NullFormatter.format_counter
formatter.NullFormatter.format_letter
formatter.NullFormatter.format_roman

One execution of Python 3a4 included in built-ins.

Python 3.0
win32
Type "help

>>next

<built-in

>>>

Do you want send and throw in it too?

[python]

Castironpi and Dennis,

WOW! Thank you very much for your examples!!!

I wasn't trolling for free development, just whether such a library
existed and/or design ideas (basic object or generator).

I had started to develop my own solution which was much more complicated
(re: ugly) than your 2 very elegant approaches.

Its interesting to compare your two very different approaches. I will to
spend some more time studying your techniques before I choose a final
approach.

Thank you both again. I'm learning a lot of Python by studying your
examples! :)

Malcolm

[python]

Castironpi,

Do you want send and throw in it too?

If its not too much trouble, I would love to see how you add these.

formatter.NullFormatter.format_counter
formatter.NullFormatter.format_letter
formatter.NullFormatter.format_roman

I'm not sure what you mean by the above lines ... <googling... are you
referencing formatter.py?
http://www.koders.com/python/fid4B7C...33DF2CA11.aspx

Thanks for your help on this - I'm learning a lot!

Malcolm

PS: "throw( up )" ... very funny! :)

[python]

Dennis,

I was a touch bored in the last hour at work today so...

Thank you!!

Malcolm