dropwhile question

[Rajanikanth Jammalamadaka]

>>list(itertool s.dropwhile(lam bda x: x<5,range(10)) )
[5, 6, 7, 8, 9]

Why doesn't this work?

>>list(itertool s.dropwhile(lam bda x: 2<x<5,range(10) ))

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Thanks,

Raj

--
"For him who has conquered the mind, the mind is the best of friends;
but for one who has failed to do so, his very mind will be the
greatest enemy."

Rajanikanth

[Marc 'BlackJack' Rintsch]

Re: dropwhile question

On Sat, 23 Aug 2008 14:54:09 -0700, Rajanikanth Jammalamadaka wrote:

>>>list(itertoo ls.dropwhile(la mbda x: x<5,range(10)) )

[5, 6, 7, 8, 9]
>
Why doesn't this work?

>>>list(itertoo ls.dropwhile(la mbda x: 2<x<5,range(10) ))

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

It *does* work. `dropwhile()` drops as long as the callable returns a
true value and then it stops dropping. First value is 0 and
``2 < 0 < 5`` is `False` so nothing is dropped.

What have you expected?

Ciao,
Marc 'BlackJack' Rintsch

[Scott David Daniels]

Re: dropwhile question

Rajanikanth Jammalamadaka wrote:

>>>list(itertoo ls.dropwhile(la mbda x: x<5,range(10)) )

[5, 6, 7, 8, 9]
>
Why doesn't this work?

>>>list(itertoo ls.dropwhile(la mbda x: 2<x<5,range(10) ))

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Because it drops _while_ the condition is True (which it is for
the first 0 entries in the sequence). What you want is:

list(x for x in range(10) if 2 < x < 5)

Note that:
list(itertools. dropwhile(lambd a x: x<5, range(10)+range (10)))
is [5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
not [5, 6, 7, 8, 9, 5, 6, 7, 8, 9].

--Scott David Daniels
Scott.Daniels.A cm.Org

[Rajanikanth Jammalamadaka]

Re: dropwhile question

Thanks for the explanations.

Regards,

Raj

On Sat, Aug 23, 2008 at 3:41 PM, Scott David Daniels
<Scott.Daniels@ acm.orgwrote:

Rajanikanth Jammalamadaka wrote:

>>>>>
>>>>list(iterto ols.dropwhile(l ambda x: x<5,range(10)) )

>>
>[5, 6, 7, 8, 9]
>>
>Why doesn't this work?

>>>>>
>>>>list(iterto ols.dropwhile(l ambda x: 2<x<5,range(10) ))

>>
>[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>
Because it drops _while_ the condition is True (which it is for
the first 0 entries in the sequence). What you want is:
>
list(x for x in range(10) if 2 < x < 5)
>
Note that:
list(itertools. dropwhile(lambd a x: x<5, range(10)+range (10)))
is [5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
not [5, 6, 7, 8, 9, 5, 6, 7, 8, 9].
>
--Scott David Daniels
Scott.Daniels.A cm.Org
--

http://mail.python.org/mailman/listinfo/python-list

>

--
"For him who has conquered the mind, the mind is the best of friends;
but for one who has failed to do so, his very mind will be the
greatest enemy."

Rajanikanth