How to create a tuple quickly with list comprehension?

[fdu.xiaojf]

Hi all,

I can use list comprehension to create list quickly. So I expected that I
can created tuple quickly with the same syntax. But I found that the
same syntax will get a generator, not a tuple. Here is my example:

In [147]: a = (i for i in range(10))

In [148]: b = [i for i in range(10)]

In [149]: type(a)
Out[149]: <type 'generator'>

In [150]: type(b)
Out[150]: <type 'list'>

Is there a way to create a tuple like (1, 2, 3, 4, 5, 6, 7, 8, 9)
quickly? I already I can use tuple() on a list which is created by list
comprehension to get a desired tuple.

Regards,

Xiao Jianfeng

[markacy]

On 13 Cze, 09:45, "[e-mail]" <[e-mail]:

Hi all,

I can use list comprehension to create list quickly. So I expected that I
can created tuple quickly with the same syntax. But I found that the
same syntax will get a generator, not a tuple. Here is my example:

In [147]: a = (i for i in range(10))

In [148]: b = [i for i in range(10)]

In [149]: type(a)
Out[149]: <type 'generator'>

In [150]: type(b)
Out[150]: <type 'list'>

Is there a way to create a tuple like (1, 2, 3, 4, 5, 6, 7, 8, 9)
quickly? I already I can use tuple() on a list which is created by list
comprehension to get a desired tuple.

Regards,

Xiao Jianfeng

You should do it like this:

>>a = tuple([i for i in range(10)])
type(a)

<type 'tuple'>

>>print a[0]

0

>>print a[9]

9

>>print a

(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)

Cheers,
Marek

[Diez B. Roggisch]

markacy wrote:

On 13 Cze, 09:45, "[e-mail]" <[e-mail]:

>Hi all,

I can use list comprehension to create list quickly. So I expected that I
can created tuple quickly with the same syntax. But I found that the
same syntax will get a generator, not a tuple. Here is my example:

In [147]: a = (i for i in range(10))

In [148]: b = [i for i in range(10)]

In [149]: type(a)
Out[149]: <type 'generator'>

In [150]: type(b)
Out[150]: <type 'list'>

Is there a way to create a tuple like (1, 2, 3, 4, 5, 6, 7, 8, 9)
quickly? I already I can use tuple() on a list which is created by list
comprehension to get a desired tuple.

Regards,

Xiao Jianfeng

You should do it like this:

>>>a = tuple([i for i in range(10)])
type(a)

<type 'tuple'>

>>>print a[0]

0

>>>print a[9]

9

>>>print a

(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)

No need to create the intermediate list, a generator expression works just
fine:

a = tuple(i for i in range(10))

Diez

[Ben Finney]

"fd********@gmail.com" <fd********@gmail.comwrites:

I can use list comprehension to create list quickly. So I expected
that I can created tuple quickly with the same syntax.

Nope. The list comprehension syntax creates lists.

But I found that the same syntax will get a generator, not a
tuple. Here is my example:

In [147]: a = (i for i in range(10))

This contains no commas, so I don't know why you think it has anything
to do with a tuple.

Bear in mind that parentheses have nothing to do with the syntax for
creating a tuple; the parentheses merely determine parsing order, and
can enclose any expression.

Is there a way to create a tuple like (1, 2, 3, 4, 5, 6, 7, 8, 9)
quickly?

tuple(range(1, 10))

--
\ "Know what I hate most? Rhetorical questions." -- Henry N. Camp |
`\ |
_o__) |
Ben Finney

[Marc 'BlackJack' Rintsch]

In <5d*************@mid.uni-berlin.de>, Diez B. Roggisch wrote:

No need to create the intermediate list, a generator expression works just
fine:

a = tuple(i for i in range(10))

But `range()` creates the intermediate list anyway. ;-)

a = tuple(xrange(10))

Ciao,

Marc 'BlackJack' Rintsch

[Bruno Desthuilliers]

fd********@gmail.com a écrit :

Hi all,

I can use list comprehension to create list quickly. So I expected that I
can created tuple quickly with the same syntax. But I found that the
same syntax will get a generator, not a tuple. Here is my example:

In [147]: a = (i for i in range(10))

In [148]: b = [i for i in range(10)]
In [149]: type(a)
Out[149]: <type 'generator'>

In [150]: type(b)
Out[150]: <type 'list'>

Is there a way to create a tuple like (1, 2, 3, 4, 5, 6, 7, 8, 9)
quickly?

t = tuple(range(1, 10))

If the use of 'range' in your above snippet was just for the exemple,
see Diez's answer.

[Dustan]

On Jun 13, 5:37 am, Marc 'BlackJack' Rintsch <[e-mail]:

In <[e-mail]>, Diez B. Roggisch wrote:

No need to create the intermediate list, a generator expression works just
fine:

a = tuple(i for i in range(10))

But `range()` creates the intermediate list anyway. ;-)

I imagine that's special case.