大约有 40,000 项符合查询结果（耗时：0.0291秒） [XML]
When should iteritems() be used instead of items()?
... more like a set (which you'd expect from a dict).
Simple example:
common_keys = list(dict_a.viewkeys() & dict_b.viewkeys())
Will give you a list of the common keys, but again, in Python 3.x - just use .keys() instead.
Python 3.x has generally been made to be more "lazy" - i.e. map is now e...
Does Python support short-circuiting?
...ent, but you could also state things very succinctly:
In [171]: name = raw_input('Enter Name: ') or '<Unkown>'
Enter Name:
In [172]: name
Out[172]: '<Unkown>'
In other words, if the return value from raw_input is true (not an empty string), it is assigned to name (nothing changes); ...
What is the difference between join and merge in Pandas?
...andas as pd
left = pd.DataFrame({'key': ['foo', 'bar'], 'val': [1, 2]}).set_index('key')
right = pd.DataFrame({'key': ['foo', 'bar'], 'val': [4, 5]}).set_index('key')
left.join(right, lsuffix='_l', rsuffix='_r')
val_l val_r
key
foo 1 4
bar 2 5
The same functi...
res.sendFile absolute path
...res.sendFile. There are two simple ways to do it:
res.sendFile(path.join(__dirname, '../public', 'index1.html'));
res.sendFile('index1.html', { root: path.join(__dirname, '../public') });
Note: __dirname returns the directory that the currently executing script is in. In your case, it looks like...
How to refer to relative paths of resources when working with a code repository
...Try to use a filename relative to the current files path. Example for './my_file':
fn = os.path.join(os.path.dirname(__file__), 'my_file')
In Python 3.4+ you can also use pathlib:
fn = pathlib.Path(__file__).parent / 'my_file'
...
What is the function __construct used for?
I have been noticing __construct a lot with classes. I did a little reading and surfing the web, but I couldn't find an explanation I could understand. I am just beginning with OOP.
...
Is there a simple way to convert C++ enum to string?
...to check out GCCXML.
Running GCCXML on your sample code produces:
<GCC_XML>
<Namespace id="_1" name="::" members="_3 " mangled="_Z2::"/>
<Namespace id="_2" name="std" context="_1" members="" mangled="_Z3std"/>
<Enumeration id="_3" name="MyEnum" context="_1" location="f0:...
(this == null) in C#!
... {
base..ctor(new Func<string>(Program.Derived.<.ctor>b__0));
return;
}
[CompilerGenerated]
private static string <.ctor>b__0()
{
string CS$1$0000;
CS$1$0000 = CS$1$0000.CheckNull();
Label_0009:
return CS$1$0000;
}
...
Why do we need virtual functions in C++?
...s to more general). Visa-versa you need an explicit cast, usually a dynamic_cast. Anything else - very prone to undefined behavior so make sure you know what you're doing. To the best of my knowledge, this has not changed since before even C++98.
– Steve314
Jun...
Mocking a class: Mock() or patch()?
...ake a look at this snippet:
>>> class MyClass(object):
... def __init__(self):
... print 'Created MyClass@{0}'.format(id(self))
...
>>> def create_instance():
... return MyClass()
...
>>> x = create_instance()
Created MyClass@4299548304
>>>
>>>...