how best to split into singleton and sequence
>>> l = []
>>> s = 'a|b'
>>> t, l = s.split('|')
>>> t
'a'
>>> l
'b'
>>> s = 'a|b|c|d'
>>> t, l = s.split('|')
Traceback (most recent call last):
File "", line 1, in ?
ValueError: too many values to unpack
>>>
so, i imagine what is happening is the lhs, t,l, is really
(t, (l)), i.e. only two items.
so how should i have done this readably and simply?
randy
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Re: OpenSource documentation problems
> I'm very sorry to say, that the Python doc is one of the worst possible > in the industry. you are entitled to a full refund -- http://mail.python.org/mailman/listinfo/python-list
Re: Arguement error
> I am wondering why I am getting this error. when I try to run a script. > TypeError: translate() takes at most 3 arguments (10 given) > but the thing is the method translate actually accepts 10 arguements. without code, how is anyone to know? -- http://mail.python.org/mailman/listinfo/python-list
Re: trictionary?
> So I'm going to try to pump you for a little more information here. Is > your goal to count, for each week, how many times it's "full" and how > many times it's "not full"? What do you use the counts for? What does > "full" mean? Is it always a 0 or 1? What's the importance of the > output formatting? 'full' is boolean. it says whether a particular bgp announcement was for the entire ip address allocation, or is a longer prefix. e.g., if an allocation was for 666.42.0.0/16 and we heard a bgp announcement for 666.42.1.0/24 that is !full, while an announcement for the prefix 666.42.0.0/16 is full. you asked :-) > for start, end, AS, full in heard: > week = int((start-startDate)/aWeek) > if week in bin: > bin[week][not full] += 1 > else: > # I'm assuming "full" takes the values 0 or 1 > # but if not, you can coerce it with bool() > bin[week] = [full, int(not full)] hmmm. this also reads well. as an old pascal and modula-2 bondage and discipline type, i gotta say is it a breath of fresh air to be in a language and community which care about how code reads more than how clever it is. randy -- http://mail.python.org/mailman/listinfo/python-list
Re: trictionary?
> bin = {}
> for start, end, AS, full in heard:
>week = int((start-startDate)/aWeek)
>counters = bin.setdefault(week, [0, 0])
>if full:
> counters[0] += 1
>else:
> counters[1] += 1
yes! thanks!
> Using an idea you used earlier, you could get smaller code by saying:
> for start, end, AS, full in heard:
>week = int((start-startDate)/aWeek)
>counters = bin.setdefault(week, [0, 0])
>counters[not full] += 1
> Or
> for start, end, AS, full in heard:
>week = int((start-startDate)/aWeek)
>bin.setdefault(week, [0, 0])[not full] += 1
> Or even
> for start, end, AS, full in heard:
> bin.setdefault(int((start-startDate)/aWeek), [0, 0])[not full] += 1
as you say, too clever.
> Using lists to represent structs is perfectly fine if the list doesn't
> live longer than about one screen of code.
i can definitely see that. in last weeks installment, i buried a
complex trinary tree in a class.
thanks for the advice!
randy
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Re: trictionary?
>> bin = {}
>> for whatever:
>>for [a, b] in foo:
>>x = 42 - a
>>if bin.has_key(x):
>> bin[x.b] += 1
>>else:
>> bin[x.b] = 1
>> bin[x.not b] = 0
>> for x, y, z in bin.iteritems():
>>print x, y, z
>>
>> should the dict value become a two element list, or is there a
>> cleaner way to do this?
> It would probably help if you explained what the real problem is
> you're trying to solve.
actually, that code fragment was meant to do that. it's pretty much
what i needed to do at that point, just the variable names made
simple.
> Using a two element list to store a pair of counts has a bad code
> smell to me.
exactly. which is why i was asking.
> That said, you could write your code something like:
> bin = {}
> for whatever:
> # NOTE: brackets are unnecessary
> for a, b in foo:
> x = 42 - a
># NOTE: 'in' is generally faster than has_key()
> if x in bin
>bin[x][0] += 1
> else:
> bin[x] = [1, 0]
> # NOTE: extra parens necessary to unpack count list
> for x, (y, z) in bin.iteritems():
> print x, y, z
so, to do this using the real names, it looks like
for [start, end, AS, full] in heard:
week = int((start-startDate)/aWeek)
if week in bin:
if full:
bin[week][0] += 1
else:
bin[week][1] += 1
else:
if full:
bin[week] = [1, 0]
else:
bin[week] = [0, 1]
...
for i, (j, k) in bin.iteritems():
if j == 0:
print str(i) + ",," + str(k)
elif k == 0:
print str(i) + "," + str(j)
else:
print str(i) + "," + str(j) + "," + str(k)
which is still pretty darned grotty and unexpressive. of course,
i could be a bit more obscure and do
if week in bin:
bin[week][not full] += 1
else:
bin[week] = [ full, not full ]
except i probably have to coerce the types or something. less
code but less obvious.
randy
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trictionary?
i have some code which looks kinda like
bin = {}
for whatever:
for [a, b] in foo:
x = 42 - a
y = 42 - b
if bin.has_key(x):
bin[x] += 1
else:
bin[x] = 1
for i, j in bin.iteritems():
print i, j
now i want to add a second count column, kinda like
bin = {}
for whatever:
for [a, b] in foo:
x = 42 - a
if bin.has_key(x):
bin[x.b] += 1
else:
bin[x.b] = 1
bin[x.not b] = 0
for x, y, z in bin.iteritems():
print x, y, z
should the dict value become a two element list, or is
there a cleaner way to do this?
randy
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Re: list insertion
>>hold = self.next >>self.next = DaClass(value) >>self.next.next = hold >> >> but i suspect (from print statement insertions) that the result >> is not as i expect. as the concept and code should be very >> common, as i am too old for pride, i thought i would ask. > I think you're fine. indeed. the bug was elsewhere. i got confused and tried to look-ahead too far when i could have just recursed. i threw away the too-clever code and replaced it with one line. i love it when that happens. randy -- http://mail.python.org/mailman/listinfo/python-list
Re: Experience regarding Python tutorials?
> There is also a python tutor newsgroup at gmane > (gmane.comp.python.tutor). is there a mailing list to which it is gated? randy -- http://mail.python.org/mailman/listinfo/python-list
Re: need a little help with time
i am doing disgusting looking junk based on calendar. example
now = calendar.timegm(time.gmtime())
aWeek = 7*24*60*60
print time.strftime('%Y-%m-%d %H:%M:%S', time.gmtime(now + aWeek))
randy
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Re: Jargons of Info Tech industry
i left the usenet in the latter half of the '80s. a few weeks ago i decided i wanted to do a new project with a new language, and chose python. so i joined this mailing list, which is gated to the usenet. i am impressed that the s:n has not gotten significantly worse than when i left, about 0.25, this message being my contribution to the noise. the s here is pretty darn good. but the n is pretty silly. randy -- http://mail.python.org/mailman/listinfo/python-list
Re: list insertion
>> hold = self.next >> self.next = DaClass(value) >> self.next.next = hold > shouldn't that last line be this? > self.next.prev = hold single threaded list > What did you expect, and what did you ovserve? i will try to distill a case randy -- http://mail.python.org/mailman/listinfo/python-list
list insertion
i am trying to insert into a singly linked list hold = self.next self.next = DaClass(value) self.next.next = hold but i suspect (from print statement insertions) that the result is not as i expect. as the concept and code should be very common, as i am too old for pride, i thought i would ask. mahalo, randy -- http://mail.python.org/mailman/listinfo/python-list
Re: loop in python
computers are cheap. i am expensive. give me clear and maintainable code every time. randy -- http://mail.python.org/mailman/listinfo/python-list
Re: dict duplicity
> Firstly, to remove one possible source of confusion, change the name of > your dictionary ... "mydict" or "fred" ... anything but "dict" > > Next, after you have created the dictionary and added items to it, do this: > print len(fred) > print len(fred.items()) > nitems = 0 > for k, v in fred.iteritems(): > nitems += 1 > print nitems > > If by this stage you haven't worked out what you are doing wrong, post > an exact copy/paste of the MINIMAL code that exhibits the "multiple > instances of same key in .iteritems()" problem i did not work out what i was doing wrongly. but now it works. i hate ing magic! but thanks for making me permute. randy -- http://mail.python.org/mailman/listinfo/python-list
Re: dict duplicity
>> a dict written as
>>
>>pKey = (prefix, pLen, origin)
>>
>>val = dict.get(pKey)
>>if val == None:
>> dict[pKey] = (timeB, timeB)
>>else:
>> if val[0]> timeB: val[0] = timeB
>> if val[1] < timeB: val[1] = timeB
>> dict[pKey] = val
>>
>> and read back as
>>
>>for pKey, pVal in dict.iteritems():
>> print \
>> pKey[0], hash(pKey[0]), \
>> pKey[1], hash(pKey[1]), \
>> pKey[2], hash(pKey[2]), \
>> "hash=", hash(pKey), \
>> pVal[0], hash(pVal[0]), \
>> pVal[1], hash(pVal[1])
>>
>> when run with | sort, produces
>>
>> 12.0.0.0 -2054516913 8 8 7018 329707286 hash= -604503432 917088000 917088000
>> 917088000 917088000
>> 12.0.0.0 -2054516913 8 8 7018 329707286 hash= -604503432 917088000 917088000
>> 917088000 917088000
>> 12.0.0.0 -2054516913 8 8 7018 329707286 hash= -604503432 917088000 917088000
>> 917088000 917088000
>> 12.0.0.0 -2054516913 8 8 7018 329707286 hash= -604503432 917088000 917088000
>> 917088000 917088000
>> 12.0.0.0 -2054516913 9 -1293912648 7018 329707286 hash= -1578430040
>> 917088000 917088000 917088000 917088000
>> 12.0.0.0 -2054516913 9 -1293912648 7018 329707286 hash= -1578430040
>> 917088000 917088000 917088000 917088000
>>
>> not that there are two entries with the same hash=
>>
>> i am utterly confused
>>
>> randy
>>
> I'm not sure I got your question but having the same hash(key) is not
> having the same key for a dict.
>
> >>> {-1:0,-2:0}
> {-2: 0, -1: 0}
> >>> hash(-1)!=hash(-2)
> False
>
> A key lookup in a dict involve real keys comparisons via '==' among the
> keys of the bin identified by the hash of the key.
ack. my point was the key touple and its hash are identical for
each pair of entries.
i executed the write section 55953 times. the iteritems gets me
111906 entries.
while it did not charge extra, it kinda spoils my code :-)
randy
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dict duplicity
a dict written as pKey = (prefix, pLen, origin) val = dict.get(pKey) if val == None: dict[pKey] = (timeB, timeB) else: if val[0] > timeB: val[0] = timeB if val[1] < timeB: val[1] = timeB dict[pKey] = val and read back as for pKey, pVal in dict.iteritems(): print \ pKey[0], hash(pKey[0]), \ pKey[1], hash(pKey[1]), \ pKey[2], hash(pKey[2]), \ "hash=", hash(pKey), \ pVal[0], hash(pVal[0]), \ pVal[1], hash(pVal[1]) when run with | sort, produces 12.0.0.0 -2054516913 8 8 7018 329707286 hash= -604503432 917088000 917088000 917088000 917088000 12.0.0.0 -2054516913 8 8 7018 329707286 hash= -604503432 917088000 917088000 917088000 917088000 12.0.0.0 -2054516913 8 8 7018 329707286 hash= -604503432 917088000 917088000 917088000 917088000 12.0.0.0 -2054516913 8 8 7018 329707286 hash= -604503432 917088000 917088000 917088000 917088000 12.0.0.0 -2054516913 9 -1293912648 7018 329707286 hash= -1578430040 917088000 917088000 917088000 917088000 12.0.0.0 -2054516913 9 -1293912648 7018 329707286 hash= -1578430040 917088000 917088000 917088000 917088000 not that there are two entries with the same hash= i am utterly confused randy -- http://mail.python.org/mailman/listinfo/python-list
