# Reverse function python? How to use?

Discussion in 'Python' started by frankie_85, Oct 29, 2006.

1. ### frankie_85Guest

Ok I'm really lost (I'm new to python) how to use the reverse function.

I made a little program which basically the a, b, c, d, e which I have
listed below and basically I want it th result to be printed reverse so
instead doing "print e, d, c, b, a", I'd like to use the reverse
function

Can someone give pointersguidelines / on how to do it?

Code (Text):

a = str(math.sqrt(math.fabs(x1)) + 5*((math.pow(x1,3))))
b = str(math.sqrt(math.fabs(x2)) + 5*((math.pow(x2,3))))
c = str(math.sqrt(math.fabs(x3)) + 5*((math.pow(x3,3))))
d = str(math.sqrt(math.fabs(x4)) + 5*((math.pow(x4,3))))
e = str(math.sqrt(math.fabs(x5)) + 5*((math.pow(x5,3))))

frankie_85, Oct 29, 2006

2. ### Nick VatamaniucGuest

Re: Reverse function python? How to use?

Use the list's reverse() function. The only thing to keep in mind is
that it will reverse in-place.
Here is an example:
--------------------------------
In [1]: l=[1,2,3]

In [2]: l.reverse()

In [3]: l
Out[3]: [3, 2, 1]
------------------------------------
So you could accumulate your results in a list then apply reverse() on
it.

Hope this helps,
Nick Vatamaniuc

frankie_85 wrote:
> Ok I'm really lost (I'm new to python) how to use the reverse function.
>
>
> I made a little program which basically the a, b, c, d, e which I have
> listed below and basically I want it th result to be printed reverse so
> instead doing "print e, d, c, b, a", I'd like to use the reverse
> function
>
> Can someone give pointersguidelines / on how to do it?
>
>
Code (Text):

>     a = str(math.sqrt(math.fabs(x1)) + 5*((math.pow(x1,3))))
>     b = str(math.sqrt(math.fabs(x2)) + 5*((math.pow(x2,3))))
>     c = str(math.sqrt(math.fabs(x3)) + 5*((math.pow(x3,3))))
>     d = str(math.sqrt(math.fabs(x4)) + 5*((math.pow(x4,3))))
>     e = str(math.sqrt(math.fabs(x5)) + 5*((math.pow(x5,3))))
>
>

Nick Vatamaniuc, Oct 29, 2006

3. ### MuraliGuest

Re: Reverse function python? How to use?

Something like this?

Code (Text):

foo = [x1,x2,x3,x4,x5]
bar = [math.sqrt(math.fabs(x))+5*math.pow(x,3) for x in foo]
bar.reverse()
print bar

frankie_85 wrote:
> Ok I'm really lost (I'm new to python) how to use the reverse function.
>
>
> I made a little program which basically the a, b, c, d, e which I have
> listed below and basically I want it th result to be printed reverse so
> instead doing "print e, d, c, b, a", I'd like to use the reverse
> function
>
> Can someone give pointersguidelines / on how to do it?
>
>
Code (Text):

>     a = str(math.sqrt(math.fabs(x1)) + 5*((math.pow(x1,3))))
>     b = str(math.sqrt(math.fabs(x2)) + 5*((math.pow(x2,3))))
>     c = str(math.sqrt(math.fabs(x3)) + 5*((math.pow(x3,3))))
>     d = str(math.sqrt(math.fabs(x4)) + 5*((math.pow(x4,3))))
>     e = str(math.sqrt(math.fabs(x5)) + 5*((math.pow(x5,3))))
>
>

Murali, Oct 29, 2006
4. ### Ben FinneyGuest

"frankie_85" <> writes:

> I made a little program which basically the a, b, c, d, e which I
> have listed below and basically I want it th result to be printed
> reverse so instead doing "print e, d, c, b, a", I'd like to use the
> reverse function

As was pointed out before, your assignment requires you to use a
list. You're using completely distinct names instead of storing these
attention to "containers" and especially "lists".

--
\ "For of those to whom much is given, much is required." -- |
`\ John F. Kennedy |
_o__) |
Ben Finney

Ben Finney, Oct 29, 2006
5. ### Guest

Re: Reverse function python? How to use?

If you wanted to keep the original list intact, you could do...

Code (Text):

foo = [x1,x2,x3,x4,x5]
bar = [math.sqrt(math.fabs(x))+5*math.pow(x,3) for x in foo]
bar_reversed = reversed(bar)

On Oct 29, 4:23 pm, "Murali" <> wrote:
> Something like this?
>
>
Code (Text):

> foo = [x1,x2,x3,x4,x5]
> bar = [math.sqrt(math.fabs(x))+5*math.pow(x,3) for x in foo]
> bar.reverse()
> print bar
>
>
> frankie_85 wrote:
> > Ok I'm really lost (I'm new to python) how to use the reverse function.

>
> > I made a little program which basically the a, b, c, d, e which I have
> > listed below and basically I want it th result to be printed reverse so
> > instead doing "print e, d, c, b, a", I'd like to use the reverse
> > function

>
> > Can someone give pointersguidelines / on how to do it?

>
> >
Code (Text):

> >     a = str(math.sqrt(math.fabs(x1)) + 5*((math.pow(x1,3))))
> >     b = str(math.sqrt(math.fabs(x2)) + 5*((math.pow(x2,3))))
> >     c = str(math.sqrt(math.fabs(x3)) + 5*((math.pow(x3,3))))
> >     d = str(math.sqrt(math.fabs(x4)) + 5*((math.pow(x4,3))))
> >     e = str(math.sqrt(math.fabs(x5)) + 5*((math.pow(x5,3))))
> >

>

, Oct 30, 2006
6. ### Kay SchluehrGuest

Re: Reverse function python? How to use?

frankie_85 wrote:
> Ok I'm really lost (I'm new to python) how to use the reverse function.
>
>
> I made a little program which basically the a, b, c, d, e which I have
> listed below and basically I want it th result to be printed reverse so
> instead doing "print e, d, c, b, a", I'd like to use the reverse
> function

You can use extended slice operators

http://www.python.org/doc/2.3.5/whatsnew/section-slices.html [1]

This function call should do what yo expect

print [e, d, c, b, a][::-1]

[1] Does anyone know where to find a comprehensible description of
enhanced slices in the Python docs besides an an aged "What's new?"
column? Or is it intended that newbies read this
http://docs.python.org/ref/slicings.html ?

Kay Schluehr, Oct 30, 2006