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What does the caret operator (^) in Python do?
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It invokes the __xor__() or __rxor__() method of the object as needed, which for integer types does a bitwise exclusive-or.
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List all the modules that are part of a python package?
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import email
package = email
for importer, modname, ispkg in pkgutil.iter_modules(package.__path__):
print "Found submodule %s (is a package: %s)" % (modname, ispkg)
How to import them too? You can just use __import__ as normal:
import pkgutil
# this is the package we are inspecting -- for...
Dynamic instantiation from string name of a class in dynamically imported module?
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You can use getattr
getattr(module, class_name)
to access the class. More complete code:
module = __import__(module_name)
class_ = getattr(module, class_name)
instance = class_()
As mentioned below, we may use importlib
import importlib
module = importlib.imp...
How to get name of exception that was caught in Python?
...rent ways to get the name of the class of the exception:
type(exception).__name__
exception.__class__.__name__
exception.__class__.__qualname__
e.g.,
try:
foo = bar
except Exception as exception:
assert type(exception).__name__ == 'NameError'
assert exception.__class__.__name__ == '...
How to save all the variables in the current python session?
...r work:
import shelve
T='Hiya'
val=[1,2,3]
filename='/tmp/shelve.out'
my_shelf = shelve.open(filename,'n') # 'n' for new
for key in dir():
try:
my_shelf[key] = globals()[key]
except TypeError:
#
# __builtins__, my_shelf, and imported modules can not be shelved.
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Chain-calling parent initialisers in python [duplicate]
...Python 3 includes an improved super() which allows use like this:
super().__init__(args)
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How to check version of python modules?
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I suggest using pip in place of easy_install. With pip, you can list all installed packages and their versions with
pip freeze
In most linux systems, you can pipe this to grep(or findstr on Windows) to find the row for the particular package you're interest...
Best way to structure a tkinter application? [closed]
...or python 3
import tkinter as tk
class MainApplication(tk.Frame):
def __init__(self, parent, *args, **kwargs):
tk.Frame.__init__(self, parent, *args, **kwargs)
self.parent = parent
<create the rest of your GUI here>
if __name__ == "__main__":
root = tk.Tk()
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How do you calculate the average of a set of circular data? [closed]
...e, A, from a set of angle measurements
a[i] 0<=i
sum_i_from_1_to_N sin(a[i])
a = arctangent ---------------------------
sum_i_from_1_to_N cos(a[i])
The method given by starblue is computationally equivalent, but his reasons are clearer and probably program...
What do all of Scala's symbolic operators mean?
... // Syntactic sugar/composition or common method
<= // Common method
_._ // Typo, though it's probably based on Keyword/composition
:: // Common method
:+= // Common method
The exact meaning of most of these methods depend on the class that is defining them. For example, <= on Int ...