list problem...

R

Rog

Hi all,
Have been grappling with a list problem for hours...
a = [2, 3, 4, 5,.....]
b = [4, 8, 2, 6,.....]
Basicly I am trying to place a[0], b[0] in a seperate list
IF a[2] and b[2] is present.
I have tried sets, zip etc with no success.
I am tackling Euler projects with Python 3.1, with minimal
knowledge, and having to tackle the language as I progress.
Enjoyable frustration :)
 
G

geremy condra

Hi all,
Have been grappling with a list problem for hours...
a = [2, 3, 4, 5,.....]
b = [4, 8, 2, 6,.....]
Basicly I am trying to place a[0], b[0] in a seperate list
IF a[2] and b[2] is present.
I have tried sets, zip etc with no success.
I am tackling Euler projects with Python 3.1, with minimal
knowledge, and having to tackle the language as I progress.
Enjoyable frustration  :)

I'm not clear on what your actual problem is, could you restate it?

It sounds like you want to copy the ith element out of a and b into
some other list- call it c- when the (i+2)th element meets some
condition. What's the condition?

Geremy Condra
 
R

Rog

Hi all,
Have been grappling with a list problem for hours... a = [2, 3, 4,
5,.....]
b = [4, 8, 2, 6,.....]
Basicly I am trying to place a[0], b[0] in a seperate list IF a[2] and
b[2] is present.
I have tried sets, zip etc with no success. I am tackling Euler projects
with Python 3.1, with minimal knowledge, and having to tackle the
language as I progress. Enjoyable frustration  :)

I'm not clear on what your actual problem is, could you restate it?

It sounds like you want to copy the ith element out of a and b into some
other list- call it c- when the (i+2)th element meets some condition.
What's the condition?

Geremy Condra

The condition is that the i-th element is inverted, but not equal.
eg 4,2 - 2,4 , 34,5 - 5,34 etc.
Hope that is clearer.
Thanks for the response.
 
S

Steven D'Aprano

Hi all,
Have been grappling with a list problem for hours... a = [2, 3, 4,
5,.....]
b = [4, 8, 2, 6,.....]
Basicly I am trying to place a[0], b[0] in a seperate list IF a[2] and
b[2] is present.
I have tried sets, zip etc with no success. I am tackling Euler
projects with Python 3.1, with minimal knowledge, and having to tackle
the language as I progress. Enjoyable frustration  :)

I'm not clear on what your actual problem is, could you restate it?

It sounds like you want to copy the ith element out of a and b into
some other list- call it c- when the (i+2)th element meets some
condition. What's the condition?

Geremy Condra

The condition is that the i-th element is inverted, but not equal. eg
4,2 - 2,4 , 34,5 - 5,34 etc.
Hope that is clearer.

Clear as mud.

Perhaps you should given an example. Given input

a = [2, 3, 4, 5, 6, 7]
b = [4, 8, 2, 6, 10, 42]

what output are you expecting, and how would you work it out by hand?
 
B

bruno.desthuilliers

Hi all,
Have been grappling with a list problem for hours... a = [2, 3, 4,
5,.....]
b = [4, 8, 2, 6,.....]
Basicly I am trying to place a[0], b[0] in a seperate list IF a[2] and
b[2] is present.
I have tried sets, zip etc with no success. I am tackling Euler
projects with Python 3.1, with minimal knowledge, and having to tackle
the language as I progress. Enjoyable frustration  :)
I'm not clear on what your actual problem is, could you restate it?
It sounds like you want to copy the ith element out of a and b into
some other list- call it c- when the (i+2)th element meets some
condition. What's the condition?
Geremy Condra
The condition is that the i-th element is inverted, but not equal. eg
4,2 - 2,4 , 34,5 - 5,34 etc.
Hope that is clearer.

Clear as mud.

Perhaps you should given an example. Given input

a = [2, 3, 4, 5, 6, 7]
b = [4, 8, 2, 6, 10, 42]

what output are you expecting,

AFAICT, the OP expects [2, 4] in this case, but it's not clear what
he'd expect for let's say:

a = [2, 3, 21, 4, 5, 6, 7]
b = [4, 8, 22, 2, 6, 10, 42]

(the 'reversed' pair is at i+3, not i+2)

or

a = [0, 2, 3, 4, 5, 6, 7]
b = [3, 4, 8, 2, 6, 10, 42]

(the first pair is at pos 1, not 0)

or

a = [2, 3, 4, 8, 6, 7]
b = [4, 8, 2, 3, 10, 42]

(there's a second 'non-reversed/reversed' match at positions resp. 1 &
3)
 
R

Rog

Hi all,
Have been grappling with a list problem for hours... a = [2, 3, 4,
5,.....]
b = [4, 8, 2, 6,.....]
Basicly I am trying to place a[0], b[0] in a seperate list IF a[2]
and b[2] is present.
I have tried sets, zip etc with no success. I am tackling Euler
projects with Python 3.1, with minimal knowledge, and having to
tackle the language as I progress. Enjoyable frustration  :)
I'm not clear on what your actual problem is, could you restate it?
It sounds like you want to copy the ith element out of a and b into
some other list- call it c- when the (i+2)th element meets some
condition. What's the condition?
Geremy Condra
The condition is that the i-th element is inverted, but not equal. eg
4,2 - 2,4 , 34,5 - 5,34 etc.
Hope that is clearer.

Clear as mud.

Perhaps you should given an example. Given input

a = [2, 3, 4, 5, 6, 7]
b = [4, 8, 2, 6, 10, 42]

what output are you expecting,

AFAICT, the OP expects [2, 4] in this case, but it's not clear what he'd
expect for let's say:

a = [2, 3, 21, 4, 5, 6, 7]
b = [4, 8, 22, 2, 6, 10, 42]

(the 'reversed' pair is at i+3, not i+2)

or

a = [0, 2, 3, 4, 5, 6, 7]
b = [3, 4, 8, 2, 6, 10, 42]

(the first pair is at pos 1, not 0)

or

a = [2, 3, 4, 8, 6, 7]
b = [4, 8, 2, 3, 10, 42]

(there's a second 'non-reversed/reversed' match at positions resp. 1 & 3)


It is true that I would have needed any 'non-reversed/reversed' pairs,
these would have been the amicable pairs I was looking for.
The method to recognise them eluded me. Eyes are not good enough :)
I have now joined Python-List and will follow the correct route.
I have used a method suggested that has made the problem redundant,
though it will bug me from now on.

g = []

def divsum(n):
return sum(i for i in range(1, n) if not n % i)

for x in range(10000, 2, -1):
c = divsum(x)
v = divsum(c)
if v == x and v != c:
g.append(divsum(x))
else:
continue

print(sum(g))
 

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question

Members online

No members online now.

Forum statistics

Threads
473,744
Messages
2,569,484
Members
44,903
Latest member
orderPeak8CBDGummies

Latest Threads

Top