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How do I change the working directory in Python?
cd is the shell command to change the working directory.
14 Answers
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if A vs if A is not None:
...if A:
will call A.__nonzero__() (see Special method names documentation) and use the return value of that function. Here's the summary:
object.__nonzero__(self)
Called to implement truth value testing and the built-in operation bool(); should return False or True, or their integer equival...
Why does GCC generate 15-20% faster code if I optimize for size instead of speed?
I first noticed in 2009 that GCC (at least on my projects and on my machines) have the tendency to generate noticeably faster code if I optimize for size ( -Os ) instead of speed ( -O2 or -O3 ), and I have been wondering ever since why.
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Django set field value after a form is initialized
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Yes, this is my problem, too. And changing form.data['Email'] is not possible.
– GergelyPolonkai
May 26 '15 at 12:30
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Call a python function from jinja2
I am using jinja2, and I want to call a python function as a helper, using a similar syntax as if I were calling a macro. jinja2 seems intent on preventing me from making a function call, and insists I repeat myself by copying the function into a template as a macro.
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What is the most pythonic way to check if an object is a number?
...ts rather than what it is, perform your operations as if you have a number and use exceptions to tell you otherwise.
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Map over object preserving keys
...h Underscore
Underscore provides a function _.mapObject to map the values and preserve the keys.
_.mapObject({ one: 1, two: 2, three: 3 }, function (v) { return v * 3; });
// => { one: 3, two: 6, three: 9 }
DEMO
With Lodash
Lodash provides a function _.mapValues to map the values and pre...
Can I create links with 'target=“_blank”' in Markdown?
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Ya know what? I agree with you and alex. I decided not to use _blank at all. It's a better user experience to keep things in one browser. They can just hit back or command-click (Mac user here :)), like you say.
– ma11hew28
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Input from the keyboard in command line application
I am attempting to get the keyboard input for a command line app for the new Apple programming language Swift.
19 Answers
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Declaring variables inside or outside of a loop
...that str absolutely ought to be declared within the while loop. No ifs, no ands, no buts.
The only case where this rule might be violated is if for some reason it is of vital importance that every clock cycle must be squeezed out of the code, in which case you might want to consider instantiating s...