On 6/7/07, David Joyner <[EMAIL PROTECTED]> wrote:
>
> though for some reason it doesn't work on strings:
>
> sage: sum(["S","A","G","E"])
> ---------------------------------------------------------------------------
> <type 'exceptions.TypeError'> Traceback (most recent call last)
>
> /mnt/hd200/sagefiles/sage-2.5.alpha2/<ipython console> in <module>()
>
> <type 'exceptions.TypeError'>: unsupported operand type(s) for +:
> 'int' and 'str'
The Python documentation for sum very specifically disallows summing
strings for mysterious reasons:
sum(sequence, start=0) -> value
Returns the sum of a sequence of numbers (NOT strings) plus the value
of parameter 'start'. When the sequence is empty, returns start.
----
With sum you often have to give the start value, but with strings that
doesn't work:
sage: sum(['S', 'A', 'G', 'E'], '')
---------------------------------------------------------------------------
<type 'exceptions.TypeError'> Traceback (most recent call last)
/Users/was/<ipython console> in <module>()
<type 'exceptions.TypeError'>: sum() can't sum strings [use
''.join(seq) instead]
sage:
-----
I think it must be some sort of efficiency issue, where ''.join(...)
is much faster, or something.
william
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