Re: [Tutor] Clustering?

[Alan Gauld]

"Carlos" <[EMAIL PROTECTED]> wrote

>>> from cluster import *
>>> data = [12,34,23,32,46,96,13]
>>> cl = HierarchicalClustering(data, lambda x,y: abs(x-y))
>>> cl.getlevel(10) # get clusters of items closer than 10
 [96, 46, [12, 13, 23, 34, 32]]

> I would like to give it a try because I have the impression that it 
> can
> be helpful too. My problem now is the lambda function, I was 
> wondering
> if someone could be so kind as to give me an example that could work 
> in
> my list with nested tuples.

lambda is just a shorthand way of writing a simple function.
You don't need to use lambda. The above line could have
been done thisaway:

>>> def f(x,y): return abs(x-y)
>>> cl = HierarchicalClustering(data, f)

So provided you can write a function to do what you want you
don't need the lambda if it confuses you.

In a general sense:

def f(p): return expression

is the same as

f = lambda p: expression

So anywhere that a function name is nmeeded you can
put a lambda.

HTH,


-- 
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld 


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Re: [Tutor] Clustering?

[Carlos]

Hallo ,

Andre thanks a lot for your help, seems to me like  my script can work 
with your function.

I found this searching the internet:

cluster 1.1.1b2
python-cluster is a "simple" package that allows to create several 
groups (clusters) of objects from a list

>>> from cluster import *
>>> data = [12,34,23,32,46,96,13]
>>> cl = HierarchicalClustering(data, lambda x,y: abs(x-y))
>>> cl.getlevel(10) # get clusters of items closer than 10
[96, 46, [12, 13, 23, 34, 32]]
>>> cl.getlevel(5)  # get clusters of items closer than 5
[96, 46, [12, 13], 23, [34, 32]]


I would like to give it a try because I have the impression that it can 
be helpful too. My problem now is the lambda function, I was wondering 
if someone could be so kind as to give me an example that could work in 
my list with nested tuples.

Thanks again!
Carlos



Andre Engels wrote:
> 2007/1/16, Carlos <[EMAIL PROTECTED] >:
>
> Hello to everybody,
>
> I have a question that I think is a little related to clustering,
> I have
> a list of lists, like this:
>
> List = [[1,5],[6,8],[48,10],[99,56]]
>
> The list is composed by a large number of lists not just four, and
> each
> 'interior' list contains two numbers that are the location of an
> object
> in a plane, so they are X and Y coordinates, my question is:
>
> Can I use this list to evaluate how many points are in a given range?
> Thats is taking the highest and lowest values for X an Y and, lets say
> divide that range in 10 regions, then get the number of objects on
> each
> region. Is this possible? and if yes, how canI do it? I ask this
> because
> as you know my python skills are not that great :)
>
>
> First, this feels like a list of tuples rather than a list of lists; 
> however, tuples and lists don't differ that much in their behaviour, 
> so there's nothing really lost.
>
> And yes, it is possible. An inline if would be the way I would resolve 
> that:
>
> def withinrange(list,xmin,xmax,ymin,ymax):
> # Get the elements of list for which the first part of the pair is 
> between xmin and xmax
> # (inclusive) and the second between ymin and ymax.
> return [c for c in list if xmin <= c[0] <= xmax and ymin <= c[1] 
> <= ymax]
>
> The longer but clearer method of doing the same would be:
>
> def withinrange(list,xmin,xmax,ymin,ymax):
> templist = []
> for c in list:
> if xmin <= c[0] <= xmax and ymin <= c[1] <= ymax:
> templist.append(c)
> return templist
>
> -- 
> Andre Engels, [EMAIL PROTECTED] 
> ICQ: 6260644  --  Skype: a_engels
> 
>
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.432 / Virus Database: 268.16.12/630 - Release Date: 1/15/2007 
> 8:28 PM
>   

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Re: [Tutor] Clustering?

[Andre Engels]

2007/1/16, Carlos <[EMAIL PROTECTED]>:


Hello to everybody,

I have a question that I think is a little related to clustering, I have
a list of lists, like this:

List = [[1,5],[6,8],[48,10],[99,56]]

The list is composed by a large number of lists not just four, and each
'interior' list contains two numbers that are the location of an object
in a plane, so they are X and Y coordinates, my question is:

Can I use this list to evaluate how many points are in a given range?
Thats is taking the highest and lowest values for X an Y and, lets say
divide that range in 10 regions, then get the number of objects on each
region. Is this possible? and if yes, how canI do it? I ask this because
as you know my python skills are not that great :)



First, this feels like a list of tuples rather than a list of lists;
however, tuples and lists don't differ that much in their behaviour, so
there's nothing really lost.

And yes, it is possible. An inline if would be the way I would resolve that:

def withinrange(list,xmin,xmax,ymin,ymax):
   # Get the elements of list for which the first part of the pair is
between xmin and xmax
   # (inclusive) and the second between ymin and ymax.
   return [c for c in list if xmin <= c[0] <= xmax and ymin <= c[1] <=
ymax]

The longer but clearer method of doing the same would be:

def withinrange(list,xmin,xmax,ymin,ymax):
   templist = []
   for c in list:
   if xmin <= c[0] <= xmax and ymin <= c[1] <= ymax:
   templist.append(c)
   return templist

--
Andre Engels, [EMAIL PROTECTED]
ICQ: 6260644  --  Skype: a_engels
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[Tutor] Clustering?

[Carlos]

Hello to everybody,

I have a question that I think is a little related to clustering, I have 
a list of lists, like this:

List = [[1,5],[6,8],[48,10],[99,56]]

The list is composed by a large number of lists not just four, and each 
'interior' list contains two numbers that are the location of an object 
in a plane, so they are X and Y coordinates, my question is:

Can I use this list to evaluate how many points are in a given range? 
Thats is taking the highest and lowest values for X an Y and, lets say 
divide that range in 10 regions, then get the number of objects on each 
region. Is this possible? and if yes, how canI do it? I ask this because 
as you know my python skills are not that great :)

Thanks in advance for your help,
Carlos

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