array alice of [:-0] ??

[guthrie]

Beginner question! :-)

x=[1,2,3,4]
for i in range(len(x)):
print x[:-i]

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

1) The x[:-0] result seems inconsistent to me;
I get the idea that -0=0, so it is taken as x[:0] -[]
2) how then should one do this basic left-recursive subsetting (easily).

Thanks.
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

[John Machin]

On 18/07/2006 11:17 PM, guthrie wrote:

Beginner question! :-)

x=[1,2,3,4]
for i in range(len(x)):
print x[:-i]

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

1) The x[:-0] result seems inconsistent to me;
I get the idea that -0=0, so it is taken as x[:0] -[]
2) how then should one do this basic left-recursive subsetting (easily).

|>for i in range(len(x), -1, -1):
.... print x[:i]
....
[1, 2, 3, 4]
[1, 2, 3]
[1, 2]
[1]
[]

[Boris Borcic]

guthrie wrote:

Beginner question! :-)

x=[1,2,3,4]
for i in range(len(x)):
print x[:-i]

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

1) The x[:-0] result seems inconsistent to me;
I get the idea that -0=0, so it is taken as x[:0] -[]

that's what you get.

2) how then should one do this basic left-recursive subsetting (easily).

I am not sure what you mean, but replacing x[:-i] by x[:len(x)-i] you will get
continuous behavior at i==0.

[Antoon Pardon]

On 2006-07-18, guthrie <gu*****@mum.eduwrote:

Beginner question! :-)

x=[1,2,3,4]
for i in range(len(x)):
print x[:-i]

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

1) The x[:-0] result seems inconsistent to me;
I get the idea that -0=0, so it is taken as x[:0] -[]

That is correct. Negative indexes are a handy shorthand, but
they can give unexpected/strange results in a number of cases.

2) how then should one do this basic left-recursive subsetting (easily).

x=[1,2,3,4]
lng = len(x)
for i in range(lng):
print x[:lng-i]

--
Antoon Pardon

[guthrie]

Thanks all!!
---------------------

guthrie wrote:

Beginner question! :-)

x=[1,2,3,4]
for i in range(len(x)):
print x[:-i]

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

1) The x[:-0] result seems inconsistent to me;
I get the idea that -0=0, so it is taken as x[:0] -[]
2) how then should one do this basic left-recursive subsetting (easily).

Thanks.

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----