Steve R. Hastings wrote:
You could also use a function that counts all different values in a list,
reducing the list to a dictionary whose keys are the unique values from
the list. I got the idea from a discussion here on comp.lang.python; I
called my version of it tally().
d =
On Tue, 02 May 2006 18:52:48 GMT in comp.lang.python, John Salerno
[EMAIL PROTECTED] wrote:
[...]
Yeah, after trying some crazy things, I just wrote it this way:
def truth_test(seq):
truth = 0
for item in seq:
if item:
truth += 1
if truth == 1:
Dave Hansen [EMAIL PROTECTED] writes:
Well, if you want something minimalist, you could try
def truth_test(seq):
return sum(1 for item in seq if item) == 1
def truth_test(seq):
return sum(map(bool, seq)) == 1
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John Salerno wrote:
Bruno Desthuilliers wrote:
But my question (sorry, it may not have been clear) was more along the
line of : why do you worry about identity in the given snippet ?.
Actually, I kind of thought that maybe it *didn't* matter in this
particular example anyway, so my
On Tue, 02 May 2006 17:15:05 GMT, rumours say that John Salerno
[EMAIL PROTECTED] might have written:
Another thing I'm trying to do is write a function that tests to see if
a list contains exactly one true item, and the rest are false (obviously
this would have to be a list of boolean values,
bruno at modulix wrote:
John Salerno wrote:
Bruno Desthuilliers wrote:
But my question (sorry, it may not have been clear) was more along the
line of : why do you worry about identity in the given snippet ?.
Actually, I kind of thought that maybe it *didn't* matter in this
particular
Steve R. Hastings wrote:
You could also use a function that counts all different values in a list,
reducing the list to a dictionary whose keys are the unique values from
the list.
Wouldn't reducing to a set instead of a dict make more sense if all you want
to do is count uniq elements?
--
On Wed, 03 May 2006 17:51:03 +, Edward Elliott wrote:
Steve R. Hastings wrote:
You could also use a function that counts all different values in a list,
reducing the list to a dictionary whose keys are the unique values from
the list.
Wouldn't reducing to a set instead of a dict make
Boris Borcic wrote:
w == x
False
w is x
True
That's the opposite of what I want to happen.
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John Salerno wrote:
Diez B. Roggisch wrote:
I can't imagine what you're actually after here, but assuming that you
really need this
Hard to explain because I'm still trying to figure out how to do it
myself. I'm trying to solve a little puzzle using Python, even though
I'm sure it's not
John Salerno [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
Is there a way to assign multiple variables to the same value, but so
that an identity test still evaluates to False?
Make sure the value is not a singleton.
Assign them one at a time.
w=1000
x=1000
w==x
True
w is x
Hmm, classes still scare me a little, but I should consider this. The
only thing is, it is not known in advance if the propositions are true
or false, you have to figure that out yourself based on the combination
of the statements given. I don't know if this changes the idea behind
your
bruno at modulix wrote:
Now if I may ask: what is your actual problem ?
Ok, since you're so curious. :)
Here's a scan of the page from the puzzle book:
http://johnjsalerno.com/spies.png
Basically I'm reading this book to give me little things to try out in
Python. There's no guarantee that
# probably not true
a = 0
b = 0
a is b # always true
A key point is that you never really assign a value to a variable. What
you really do is bind an object reference to a name. The long,
simultaneous assignment form binds the same object reference to multiple
variables:
a = b = c = d = 12345
Steve R. Hastings wrote:
Anyway, the major point I want you to take away from all this: it doesn't
matter whether the is test succeeds or fails, if all you care about is
the *value* of a variable. Python reuses object references to save
memory, because this doesn't affect expressions that
On 2006-05-02, John Salerno [EMAIL PROTECTED] wrote:
Yeah, after trying some crazy things, I just wrote it this way:
def truth_test(seq):
truth = 0
for item in seq:
if item:
truth += 1
if truth == 1:
return True
else:
return
Steve R. Hastings wrote:
So, don't test to see if something is equal to True or False:
if 0 == False:
pass # never executed; False and 0 do not directly compare
of course they do - ie isinstance(False,int) is True and False == 0
You *could* do this, but I don't really recommend
On 2006-05-02, John Salerno [EMAIL PROTECTED] wrote:
Python knows how to count. :)
def countFalse(seq):
return len([v for v in seq if not v])
def countTrue(seq):
return len([v for v in seq if v])
def truth_test(seq):
return countTrue(seq) == 1
Gosh, so much to learn!
Grant Edwards wrote:
Python knows how to count. :)
def countFalse(seq):
return len([v for v in seq if not v])
def countTrue(seq):
return len([v for v in seq if v])
def truth_test(seq):
return countTrue(seq) == 1
I'd suggest the more direct
def countFalse(seq) :
On Tue, 02 May 2006 19:11:36 +, John Salerno wrote:
Grant Edwards wrote:
Python knows how to count. :)
def countFalse(seq):
return len([v for v in seq if not v])
def countTrue(seq):
return len([v for v in seq if v])
def truth_test(seq):
return countTrue(seq) == 1
John Salerno [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
I'm sure it's not necessary. Basically W, X, Y and Z are propositions
that are either true or false, and the puzzle lists a few statements
such as Exactly one of X, Y and Z is true, and I'm trying to work out
a little
On 2006-05-02, Boris Borcic [EMAIL PROTECTED] wrote:
Grant Edwards wrote:
Python knows how to count. :)
def countFalse(seq):
return len([v for v in seq if not v])
def countTrue(seq):
return len([v for v in seq if v])
def truth_test(seq):
return countTrue(seq) == 1
Grant Edwards wrote:
On 2006-05-02, Boris Borcic [EMAIL PROTECTED] wrote:
Grant Edwards wrote:
Python knows how to count. :)
def countFalse(seq):
return len([v for v in seq if not v])
def countTrue(seq):
return len([v for v in seq if v])
def truth_test(seq):
return
John Salerno wrote:
bruno at modulix wrote:
Now if I may ask: what is your actual problem ?
Ok, since you're so curious. :)
Here's a scan of the page from the puzzle book:
http://johnjsalerno.com/spies.png
Basically I'm reading this book to give me little things to try out in
John Salerno wrote:
bruno at modulix wrote:
Now if I may ask: what is your actual problem ?
Ok, since you're so curious. :)
Here's a scan of the page from the puzzle book:
http://johnjsalerno.com/spies.png
Basically I'm reading this book to give me little things to try out in
Python.
bruno at modulix wrote:
re-phrase it according to how Python works, and you'll get the answer:
Is there a way to bind multiple names to the same object, but so the
identity of this object is different from the identity of this object ?
Which raises an interesting parallel question: is there
Am Dienstag 02 Mai 2006 22:39 schrieb Edward Elliott:
Which raises an interesting parallel question: is there a way to clone an
arbitrary object?
Yes, check the copy module.
copy.copy() does a shallow copy of the parameter, copy.deepcopy() a deep copy
of the parameter. For the difference
Heiko Wundram wrote:
Integer and string objects
are immutable in Python, so why'd you want to have different IDs for an
object of the same value? It's the value you're working with in a program,
not the objects ID. At least it should be, if you're truly intent on
working with the
In article [EMAIL PROTECTED],
John Salerno [EMAIL PROTECTED] wrote:
bruno at modulix wrote:
Now if I may ask: what is your actual problem ?
Ok, since you're so curious. :)
Here's a scan of the page from the puzzle book:
http://johnjsalerno.com/spies.png
Basically I'm reading this book to
On 2006-05-02, Boris Borcic [EMAIL PROTECTED] wrote:
Grant Edwards wrote:
On 2006-05-02, Boris Borcic [EMAIL PROTECTED] wrote:
Grant Edwards wrote:
Python knows how to count. :)
def countFalse(seq):
return len([v for v in seq if not v])
def countTrue(seq):
return len([v for v in
John Salerno a écrit :
bruno at modulix wrote:
Now if I may ask: what is your actual problem ?
Ok, since you're so curious. :)
Sorry !-)
Here's a scan of the page from the puzzle book:
http://johnjsalerno.com/spies.png
Basically I'm reading this book to give me little things to try
Heiko Wundram a écrit :
(snip)
If you're looking for things to code in Python, I'd rather suggest you look
at
number theory than at logic problems.
Basically, every logic problem can be
solved by exhaustive search (which is always the same algorithm), whereas a
number theory problem
Heiko Wundram wrote:
Hummm... Isn't it easier and faster to solve this problem by hand than to
code
a Python program for it? I had proofs for what has to be on both papers in
about 30 seconds... ;-)
Yeah, I had actually already figured it out in my head fairly quickly.
If you're looking
Bruno Desthuilliers wrote:
But my question (sorry, it may not have been clear) was more along the
line of : why do you worry about identity in the given snippet ?.
Actually, I kind of thought that maybe it *didn't* matter in this
particular example anyway, so my question was meant to be
On 2006-05-03, John Salerno [EMAIL PROTECTED] wrote:
Bruno Desthuilliers wrote:
But my question (sorry, it may not have been clear) was more
along the line of : why do you worry about identity in the
given snippet ?.
Actually, I kind of thought that maybe it *didn't* matter in
this
On Tue, 02 May 2006 21:20:48 +0200, Boris Borcic wrote:
Steve R. Hastings wrote:
So, don't test to see if something is equal to True or False:
if 0 == False:
pass # never executed; False and 0 do not directly compare
of course they do - ie isinstance(False,int) is True and False ==
Roger Miller wrote:
Steve R. Hastings wrote:
a = 0
b = 0
a is b # always true
Is this guaranteed by the Python specification, or is it an artifact of
the current implementation?
AFAIK it's an artifact. The performance hit it Python
stopped sharing small integers could be enormous,
On Tue, 02 May 2006 12:58:14 -0700, Roger Miller wrote:
Steve R. Hastings wrote:
a = 0
b = 0
a is b # always true
Is this guaranteed by the Python specification, or is it an artifact of
the current implementation?
I believe it's an artifact of the current implementation. And I only
On Tue, 02 May 2006 21:44:21 +0200, Boris Borcic wrote:
note that generators have no defined length - precisely because they feed
values one at a time while you need them all together to speak of a
length. The second expression will raise a TypeError because of that.
Er, yes. If I had
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