Hello,
I'm boggled.
I have this function which takes a keyer that keys a table (iterable). I
filter based on these keys, then groupby based on the filtered keys and
a keyfunc. Then, to make the resulting generator behave a little nicer
(no requirement for user to unpack the keys), I strip the keys in a
generator expression that unpacks them and generates the k,g pairs I
want ("regrouped"). I then append the growing list of series generator
into the "serieses" list ("serieses" is plural for series if your
vocablulary isn't that big).
Here's the function:
def serialize(table, keyer=_keyer,
selector=_selector,
keyfunc=_keyfunc,
series_keyfunc=_series_keyfunc):
keyed = izip(imap(keyer, table), table)
filtered = ifilter(selector, keyed)
serialized = groupby(filtered, series_keyfunc)
serieses = []
for s_name, series in serialized:
grouped = groupby(series, keyfunc)
regrouped = ((k, (v[1] for v in g)) for (k,g) in grouped)
serieses.append((s_name, regrouped))
for s in serieses:
yield s
I defined a little debugging function called iterprint:
def iterprint(thing):
if isinstance(thing, str):
print thing
elif hasattr(thing, 'items'):
print thing.items()
else:
try:
for x in thing:
iterprint(x)
except TypeError:
print thing
The gist is that iterprint will print any generator down to its
non-iterable components--it works fine for my purpose here, but I
included the code for the curious.
When I apply iterprint in the following manner (only change is the
iterprint line) everything looks fine and my "regrouped" generators in
"serieses" generate what they are supposed to when iterprinting. The
iterprint at this point shows that everything is working just the way I
want (I can see the last item in "serieses" iterprints just fine).
def serialize(table, keyer=_keyer,
selector=_selector,
keyfunc=_keyfunc,
series_keyfunc=_series_keyfunc):
keyed = izip(imap(keyer, table), table)
filtered = ifilter(selector, keyed)
serialized = groupby(filtered, series_keyfunc)
serieses = []
for s_name, series in serialized:
grouped = groupby(series, keyfunc)
regrouped = ((k, (v[1] for v in g)) for (k,g) in grouped)
serieses.append((s_name, regrouped))
iterprint(serieses)
for s in serieses:
yield s
Now, here's the rub. When I apply iterprint in the following manner, it
looks like my generator ("regrouped") gets consumed (note the only
change is a two space de-dent of the iterprint call--the printing is
outside the loop):
def serialize(table, keyer=_keyer,
selector=_selector,
keyfunc=_keyfunc,
series_keyfunc=_series_keyfunc):
keyed = izip(imap(keyer, table), table)
filtered = ifilter(selector, keyed)
serialized = groupby(filtered, series_keyfunc)
serieses = []
for s_name, series in serialized:
grouped = groupby(series, keyfunc)
regrouped = ((k, (v[1] for v in g)) for (k,g) in grouped)
serieses.append((s_name, regrouped))
iterprint(serieses)
for s in serieses:
yield s
Now, what is consuming my "regrouped" generator when going from inside
the loop to outside?
Thanks in advance for any clue.
py> print version
2.5.1 (r251:54869, Apr 18 2007, 22:08:04)
[GCC 4.0.1 (Apple Computer, Inc. build 5367)]
--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095
http://www.jamesstroud.com
--
http://mail.python.org/mailman/listinfo/python-list
