flat tuple

[Will McGugan]

Hi,

What is the simplest way of turning a single value and a tuple in to a
single 'flat' tuple?

ie.

t= ( 1, 2, 3 )
n= 10

n, t gives me ( 10, ( 1, 2, 3 ) )

Fair enough, but I would like to get.. ( 10, 1, 2, 3 )

I would like to use the result to create a string with the % operator -
I was hoping there was some shorthand to produce ( n, t[0], t[1], t[2] ).

Thanks,

Will McGugan

 

[Phil Frost]

Tuples can be joined with the + operator, like so:
(1, 2, 3, 4)

so in your case, you could do (n,) + t. If you are using the result for
% formatting, it might be better to use a list, which is mutable, so
it's possible to add a new element without constructing a new list, like
so:

t = [1,2,3]
t.insert(0, 10)
t

[10, 1, 2, 3]

If you have many things to concatenate, you can use the builtin function
reduce to do it, like so:

l = [[1,2,3],[4,5],[6]]
reduce(lambda a, b: a.extend(b) or a, l, [])

[1, 2, 3, 4, 5, 6]

Hi,

What is the simplest way of turning a single value and a tuple in to a
single 'flat' tuple?

ie.

t= ( 1, 2, 3 )
n= 10

n, t gives me ( 10, ( 1, 2, 3 ) )

Fair enough, but I would like to get.. ( 10, 1, 2, 3 )

I would like to use the result to create a string with the % operator -
I was hoping there was some shorthand to produce ( n, t[0], t[1], t[2] ).

Thanks,

Will McGugan

 

[Duncan Booth]

What is the simplest way of turning a single value and a tuple in to a
single 'flat' tuple?

ie.

t= ( 1, 2, 3 )
n= 10

n, t gives me ( 10, ( 1, 2, 3 ) )

Fair enough, but I would like to get.. ( 10, 1, 2, 3 )

I would like to use the result to create a string with the % operator -
I was hoping there was some shorthand to produce ( n, t[0], t[1], t[2] ).

Tuples support concatenation so all you have to do is to wrap n in a tuple
then add them together:

format % ((n,) + t)

 

[Alex Martelli]

Hi,

What is the simplest way of turning a single value and a tuple in to a
single 'flat' tuple?

ie.

t= ( 1, 2, 3 )
n= 10

n, t gives me ( 10, ( 1, 2, 3 ) )

Simplest is probably:

(n,) + t


Alex

 

[Alex Martelli]

Tuples can be joined with the + operator, like so:

(1, 2, 3, 4)

so in your case, you could do (n,) + t. If you are using the result for
% formatting, it might be better to use a list, which is mutable, so

Might be, but % wants a tuple as the RHS (assuming the LHS format string
has multiple %-formatting elements), NOT a list.


Alex

 

[John Lenton]

Might be, but % wants a tuple as the RHS (assuming the LHS format string
has multiple %-formatting elements), NOT a list.

you mean it actually converts it into a tuple?

--
John Lenton ([email protected]) -- Random fortune:
Most public domain software is free, at least at first glance.

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[Peter Hansen]

you mean it actually converts it into a tuple?

This isn't that hard to test:

c:\>python

>>> 'testing %s %s' % ['use of', 'a list']

Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: not enough arguments for format string

-Peter