Python’s ModulesWhat is a module?Module’s Cont’d… # Fibonacci numbers module def fib(n): # write Fibonacci series up to n a, b = 0, 1 while b < n: print b, a, b = b, a+b def fib2(n): # return Fibonacci series up to n result = [] a, b = 0, 1 while b < n: result.append(b) a, b = b, a+b return resultModule’s cont’d… >>> import fibo >>> fibo.fib(1000) 1 1 2 3 5 8 13 21 34 55 89 144 233 >>> fibo.fib2(100) [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89] >>> fibo.__name__ 'fibo' >>> fib = fibo.fib >>> fib(500) 1 1 2 3 5 8 13 21 34 55 89 144 233 377Module’s Cont’d…The Module Search Path“Compiled” Python files“Compiled” Python files cont’dThe dir() FunctionThe dir() Function cont’d…PackagesSlide 12Packages cont’d…Importing * From a PackageQ U E S T I O N SPython’s Modulesby E. Esin GOKGOZWhat is a module? a file containing Python definitions and statementsdefinitions from a module can be imported into other modules or into the main moduleThe file name is the module name with the suffix .py appendedModule’s Cont’d…# Fibonacci numbers module def fib(n): # write Fibonacci series up to n a, b = 0, 1 while b < n: print b, a, b = b, a+b def fib2(n): # return Fibonacci series up to n result = [] a, b = 0, 1 while b < n: result.append(b) a, b = b, a+b return resultModule’s cont’d…>>> import fibo >>> fibo.fib(1000) 1 1 2 3 5 8 13 21 34 55 89 144 233 >>> fibo.fib2(100) [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89] >>> fibo.__name__ 'fibo' >>> fib = fibo.fib >>> fib(500) 1 1 2 3 5 8 13 21 34 55 89 144 233 377Module’s Cont’d…Modules can import other modules>>> from fibo import fib, fib2 >>> fib(500) 1 1 2 3 5 8 13 21 34 55 89 144 233 377>>> from fibo import * >>> fib(500) 1 1 2 3 5 8 13 21 34 55 89 144 233 377The Module Search PathWhen a module named spam is imported, the interpreter searches for a file named spam.py in the current directory, and then in the list of directories specified by the environment variable PYTHONPATHWhen PYTHONPATH is not set, or when the file is not found there, the search continues in an installation-dependent default path; on Unix, this is usually .:/usr/local/lib/python“Compiled” Python filesif a file called spam.pyc exists in the directory where spam.py is found, this is assumed to contain an already-“byte-compiled” version of the module spam.“Compiled” Python files cont’dWhen the Python interpreter is invoked with the -O flag, optimized code is generated and stored in .pyo files. A program doesn’t run any faster when it is read from a .pyc or .pyo file than when it is read from a .py file; the only thing that’s faster about .pyc or .pyo files is the speed with which they are loadedThe module compileall can create .pyc files for all modules in a directory.The dir() FunctionWithout arguments, dir() lists the names you have defined currently:>>> a = [1, 2, 3, 4, 5] >>> import fibo >>> fib = fibo.fib>>> dir() ['__builtins__', '__doc__', '__file__', '__name__', 'a', 'fib', 'fibo', 'sys']The dir() Function cont’d…standard module __builtin__:>>> import __builtin__ >>> dir(__builtin__) ['ArithmeticError', 'AssertionError', 'AttributeError', 'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError', 'Exception', 'False', 'FloatingPointError', 'FutureWarning', 'IOError', 'ImportError', 'IndentationError', 'IndexError',…]PackagesPackages are a way of structuring Python’s module namespace by using “dotted module names”. e.g. the module name A.B designates a submodule named B in a package named ASound / Top-level package__init__.py Initialize the sound package formats/ Subpackage for file format conversions __init__.py wavread.pywavwrite.py aiffread.py aiffwrite.py auread.py ... effects/ Subpackage for sound effects __init__.py echo.py surround.py reverse.py ...filters/ Subpackage for filters __init__.py equalizer.py vocoder.py ...Packages cont’d…import sound.effects.echo sound.effects.echo.echofilter(input, output, delay=0.7, atten=4) from sound.effects import echo echo.echofilter(input, output, delay=0.7, atten=4) from sound.effects.echo import echofilterImporting * From a Packagefrom sound.effects import *!!! must have __all____all__ = ["echo", "surround", "reverse"]Q U E S T I O N S? ? ? ?? ? ???
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