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How to deep copy a list?
... don't make a deep copy using list() (Both list(...) and testList[:] are shallow copies).
You use copy.deepcopy(...) for deep copying a list.
deepcopy(x, memo=None, _nil=[])
Deep copy operation on arbitrary Python objects.
See the following snippet -
>>> a = [[1, 2, 3], [4, 5, 6]]...
How to overcome TypeError: unhashable type: 'list'
...used to compare dictionary keys during a dictionary lookup quickly.
Internally, hash() method calls __hash__() method of an object which are set by default for any object.
Converting a nested list to a set
>>> a = [1,2,3,4,[5,6,7],8,9]
>>> set(a)
Traceback (most recent call last...
Why use def main()? [duplicate]
...ink I still have something else to add.
Reasons to have that if statement calling main() (in no particular order):
Other languages (like C and Java) have a main() function that is called when the program is executed. Using this if, we can make Python behave like them, which feels more familiar for ...
Python os.path.join on Windows
...'c:' 'c:\\' did not work (C:\\ created two backslashes, C:\ didn't work at all) Thanks again ghostdog74, Smashery, and Roger Pate. I am in your debt :)
– Frank E.
Mar 11 '10 at 6:12
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Removing multiple keys from a dictionary safely
...
Why not like this:
entries = ('a', 'b', 'c')
the_dict = {'b': 'foo'}
def entries_to_remove(entries, the_dict):
for key in entries:
if key in the_dict:
del the_dict[key]
A more compact version was provided by mattbornski using dict.pop()
...
Update relationships when saving changes of EF4 POCO objects
...ost to context. After attaching object to context the state of the object, all related objects and all relations is set to Unchanged.
Use context.ObjectStateManager.ChangeObjectState to set your BlogPost to Modified
Iterate through Tag collection
Use context.ObjectStateManager.ChangeRelationshipStat...
Removing duplicate objects with Underscore for Javascript
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.uniq/.unique accepts a callback
var list = [{a:1,b:5},{a:1,c:5},{a:2},{a:3},{a:4},{a:3},{a:2}];
var uniqueList = _.uniq(list, function(item, key, a) {
return item.a;
});
// uniqueList = [Object {a=1, b=5}, Object {a=2}, Object {a=3}, Object ...
代码块超过1.2w编译apk报错问题 - App Inventor 2 中文网 - 清泛IT社区，为创新赋能！
...ng.api.ApiProxy$RequestTooLargeException: The request to API call datastore_v3.Put() was too large.
at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:416)
at com.google.gwt.user.server.rpc.RPC.invokeAnd...
How to obtain a Thread id in Python?
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Using the logging module you can automatically add the current thread identifier in each log entry.
Just use one of these LogRecord mapping keys in your logger format string:
%(thread)d : Thread ID (if available).
%(threadName)s : Thread name (if available).
a...
Static methods in Python?
Is it possible to have static methods in Python which I could call without initializing a class, like:
10 Answers
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