In article <[EMAIL PROTECTED]>,
"Raymond Hettinger" <[EMAIL PROTECTED]> wrote:
> The rationale is to replace the awkward and slow existing idioms for
> dictionary
> based accumulation:
>
> d[key] = d.get(key, 0) + qty
> d.setdefault(key, []).extend(values)
>
> In simplest form, those two statements would now be coded more readably as:
>
> d.count(key)
> d.appendlist(key, value)
>
> In their multi-value forms, they would now be coded as:
>
> d.count(key, qty)
> d.appendlist(key, *values)
>
> The error messages returned by the new methods are the same as those returned
> by
> the existing idioms.
>
> The get() method would continue to exist because it is useful for
> applications
> other than accumulation.
>
> The setdefault() method would continue to exist but would likely not make it
> into Py3.0.
The other dictionary based accumulation I've used but don't see here is
with sets as dictionary values, i.e.
dictionary.setdefault(key,set()).add(value).
I suppose it would be possible to appendlist then make a set from the
list, but if you were to take that minimalist philosophy to an extreme
you wouldn't need count either, you could just appendlist then use len.
--
David Eppstein
Computer Science Dept., Univ. of California, Irvine
http://www.ics.uci.edu/~eppstein/
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