Zip documentation

Unlike ARC,. ZIP files have capability to store multiple files using different compression techniques while at the same time supports storing a file without any compression. In order to render the compressed files, a ZIP archive holds a directory at its end that keeps the entry of the contained files and their location in the archive file.

It, thus, plays the role of encoding for encapsulating information necessary to render the compressed files. The format keeps dual copies of the directory structure to provide greater protection against loss of data. Each file in a ZIP archive is represented as an individual entry where each entry consists of a Local File Header followed by the compressed file data.

The Directory at the end of archive holds the references to all these file entries. ZIP file readers should avoid reading the local file headers and all sort of file listing should be read from the Directory. This Directory is the only source for valid file entries in the archive as files can be appended towards the end of the archive as well. That is why if a reader reads local headers of a ZIP archive from the beginning, it may read invalid deleted entries as well those are not part of the Directory being deleted from archive.

The order of the file entries in the central directory need not coincide with the order of file entries in the archive. The Local File Header of each entry represents information about the file such as comment, file size and file name.

The extra data fields optional can accommodate information for extensibility options of the ZIP format. The Local File Header has specific field structure consisting of multi-byte values. All the values are stored in little-endian byte order where the field length counts the length in bytes.

Equivalent to calling x. Note: Unlike iter , aiter has no 2-argument variant. Return True if all elements of the iterable are true or if the iterable is empty. Equivalent to:. When awaited, return the next item from the given asynchronous iterator , or default if given and the iterator is exhausted. This is the async variant of the next builtin, and behaves similarly.

Awaiting this returns the next value of the iterator. If default is given, it is returned if the iterator is exhausted, otherwise StopAsyncIteration is raised. Return True if any element of the iterable is true. If the iterable is empty, return False.

This generates a string similar to that returned by repr in Python 2. The result is a valid Python expression. Some examples:. See also format for more information. Return a Boolean value, i. If x is false or omitted, this returns False ; otherwise, it returns True. The bool class is a subclass of int see Numeric Types — int, float, complex. It cannot be subclassed further. Its only instances are False and True see Boolean Values. Changed in version 3. This function drops you into the debugger at the call site.

Specifically, it calls sys. By default, sys. However, sys. Raises an auditing event builtins. Return a new array of bytes.

It has most of the usual methods of mutable sequences, described in Mutable Sequence Types , as well as most methods that the bytes type has, see Bytes and Bytearray Operations.

The optional source parameter can be used to initialize the array in a few different ways:. If it is a string , you must also give the encoding and optionally, errors parameters; bytearray then converts the string to bytes using str.

If it is an integer , the array will have that size and will be initialized with null bytes. If it is an object conforming to the buffer interface , a read-only buffer of the object will be used to initialize the bytes array.

Accordingly, constructor arguments are interpreted as for bytearray. Bytes objects can also be created with literals, see String and Bytes literals.

Return True if the object argument appears callable, False if not. If this returns True , it is still possible that a call fails, but if it is False , calling object will never succeed. New in version 3. Return the string representing a character whose Unicode code point is the integer i. This is the inverse of ord. The valid range for the argument is from 0 through 1,, 0x10FFFF in base ValueError will be raised if i is outside that range. A class method receives the class as an implicit first argument, just like an instance method receives the instance.

To declare a class method, use this idiom:. The classmethod form is a function decorator — see Function definitions for details. A class method can be called either on the class such as C. The instance is ignored except for its class. If a class method is called for a derived class, the derived class object is passed as the implied first argument. If you want those, see staticmethod in this section. For more information on class methods, see The standard type hierarchy.

Compile the source into a code or AST object. Code objects can be executed by exec or eval. Refer to the ast module documentation for information on how to work with AST objects. The mode argument specifies what kind of code must be compiled; it can be 'exec' if source consists of a sequence of statements, 'eval' if it consists of a single expression, or 'single' if it consists of a single interactive statement in the latter case, expression statements that evaluate to something other than None will be printed.

If neither is present or both are zero the code is compiled with the same flags that affect the code that is calling compile. Compiler options and future statements are specified by bits which can be bitwise ORed together to specify multiple options. The argument optimize specifies the optimization level of the compiler; the default value of -1 selects the optimization level of the interpreter as given by -O options.

This function raises SyntaxError if the compiled source is invalid, and ValueError if the source contains null bytes. If you want to parse Python code into its AST representation, see ast.

Raises an auditing event compile with arguments source and filename. This event may also be raised by implicit compilation. When compiling a string with multi-line code in 'single' or 'eval' mode, input must be terminated by at least one newline character. This is to facilitate detection of incomplete and complete statements in the code module. Also, input in 'exec' mode does not have to end in a newline anymore.

Added the optimize parameter. If the first parameter is a string, it will be interpreted as a complex number and the function must be called without a second parameter. The second parameter can never be a string. Each argument may be any numeric type including complex. If imag is omitted, it defaults to zero and the constructor serves as a numeric conversion like int and float. If both arguments are omitted, returns 0j.

For a general Python object x , complex x delegates to x. The complex type is described in Numeric Types — int, float, complex. This is a relative of setattr. The arguments are an object and a string. The function deletes the named attribute, provided the object allows it. For example, delattr x, 'foobar' is equivalent to del x. Create a new dictionary. The dict object is the dictionary class.

See dict and Mapping Types — dict for documentation about this class. For other containers see the built-in list , set , and tuple classes, as well as the collections module. Without arguments, return the list of names in the current local scope. With an argument, attempt to return a list of valid attributes for that object.

The default dir mechanism behaves differently with different types of objects, as it attempts to produce the most relevant, rather than complete, information:. If the object is a type or class object, the list contains the names of its attributes, and recursively of the attributes of its bases. Because dir is supplied primarily as a convenience for use at an interactive prompt, it tries to supply an interesting set of names more than it tries to supply a rigorously or consistently defined set of names, and its detailed behavior may change across releases.

For example, metaclass attributes are not in the result list when the argument is a class. Take two non-complex numbers as arguments and return a pair of numbers consisting of their quotient and remainder when using integer division. With mixed operand types, the rules for binary arithmetic operators apply. Return an enumerate object. The arguments are a string and optional globals and locals.

If provided, globals must be a dictionary. If provided, locals can be any mapping object. The expression argument is parsed and evaluated as a Python expression technically speaking, a condition list using the globals and locals dictionaries as global and local namespace.

If the locals dictionary is omitted it defaults to the globals dictionary. If both dictionaries are omitted, the expression is executed with the globals and locals in the environment where eval is called. Note, eval does not have access to the nested scopes non-locals in the enclosing environment.

The return value is the result of the evaluated expression. Syntax errors are reported as exceptions. This function can also be used to execute arbitrary code objects such as those created by compile. In this case, pass a code object instead of a string. If the code object has been compiled with 'exec' as the mode argument, eval 's return value will be None. Hints: dynamic execution of statements is supported by the exec function.

The globals and locals functions return the current global and local dictionary, respectively, which may be useful to pass around for use by eval or exec. See ast. Raises an auditing event exec with the code object as the argument.

Code compilation events may also be raised. This function supports dynamic execution of Python code. If it is a string, the string is parsed as a suite of Python statements which is then executed unless a syntax error occurs.

Be aware that the nonlocal , yield , and return statements may not be used outside of function definitions even within the context of code passed to the exec function. The return value is None. In all cases, if the optional parts are omitted, the code is executed in the current scope.

If only globals is provided, it must be a dictionary and not a subclass of dictionary , which will be used for both the global and the local variables. If globals and locals are given, they are used for the global and local variables, respectively. Remember that at the module level, globals and locals are the same dictionary. If exec gets two separate objects as globals and locals , the code will be executed as if it were embedded in a class definition. The built-in functions globals and locals return the current global and local dictionary, respectively, which may be useful to pass around for use as the second and third argument to exec.

The default locals act as described for function locals below: modifications to the default locals dictionary should not be attempted. Pass an explicit locals dictionary if you need to see effects of the code on locals after function exec returns. Construct an iterator from those elements of iterable for which function returns true.

If function is None , the identity function is assumed, that is, all elements of iterable that are false are removed.

Note that filter function, iterable is equivalent to the generator expression item for item in iterable if function item if function is not None and item for item in iterable if item if function is None. See itertools.

If the argument is a string, it should contain a decimal number, optionally preceded by a sign, and optionally embedded in whitespace. The argument may also be a string representing a NaN not-a-number , or positive or negative infinity. More precisely, the input must conform to the following grammar after leading and trailing whitespace characters are removed:. Here floatnumber is the form of a Python floating-point literal, described in Floating point literals.

If the argument is outside the range of a Python float, an OverflowError will be raised. For a general Python object x , float x delegates to x. If no argument is given, 0. The float type is described in Numeric Types — int, float, complex. Return a new frozenset object, optionally with elements taken from iterable.

See frozenset and Set Types — set, frozenset for documentation about this class. For other containers see the built-in set , list , tuple , and dict classes, as well as the collections module. Return the value of the named attribute of object. For example, getattr x, 'foobar' is equivalent to x.

If the named attribute does not exist, default is returned if provided, otherwise AttributeError is raised. Return the dictionary implementing the current module namespace. For code within functions, this is set when the function is defined and remains the same regardless of where the function is called. This is implemented by calling getattr object, name and seeing whether it raises an AttributeError or not.

Return the hash value of the object if it has one. Hash values are integers. They are used to quickly compare dictionary keys during a dictionary lookup. Numeric values that compare equal have the same hash value even if they are of different types, as is the case for 1 and 1. Invoke the built-in help system.

This function is intended for interactive use. If no argument is given, the interactive help system starts on the interpreter console. If the argument is a string, then the string is looked up as the name of a module, function, class, method, keyword, or documentation topic, and a help page is printed on the console.

If the argument is any other kind of object, a help page on the object is generated. For more info, see the FAQ entry on positional-only parameters. This function is added to the built-in namespace by the site module. If you want to convert an integer number to an uppercase or lower hexadecimal string with prefix or not, you can use either of the following ways:. See also int for converting a hexadecimal string to an integer using a base of To obtain a hexadecimal string representation for a float, use the float.

This is an integer which is guaranteed to be unique and constant for this object during its lifetime. Two objects with non-overlapping lifetimes may have the same id value. If the prompt argument is present, it is written to standard output without a trailing newline.

The function then reads a line from input, converts it to a string stripping a trailing newline , and returns that. If the readline module was loaded, then input will use it to provide elaborate line editing and history features. Return an integer object constructed from a number or string x , or return 0 if no arguments are given. For floating point numbers, this truncates towards zero. If x is not a number or if base is given, then x must be a string, bytes , or bytearray instance representing an integer literal in radix base.

A base-n literal consists of the digits 0 to n-1, with a to z or A to Z having values 10 to The default base is The allowed values are 0 and 2— Base 0 means to interpret exactly as a code literal, so that the actual base is 2, 8, 10, or 16, and so that int '', 0 is not legal, while int '' is, as well as int '', 8. The integer type is described in Numeric Types — int, float, complex. Previous versions used base. Return True if the object argument is an instance of the classinfo argument, or of a direct, indirect, or virtual subclass thereof.

If object is not an object of the given type, the function always returns False. If classinfo is a tuple of type objects or recursively, other such tuples or a Union Type of multiple types, return True if object is an instance of any of the types. If classinfo is not a type or tuple of types and such tuples, a TypeError exception is raised. Return True if class is a subclass direct, indirect, or virtual of classinfo.

A class is considered a subclass of itself. In any other case, a TypeError exception is raised. Return an iterator object. The first argument is interpreted very differently depending on the presence of the second argument.

If it does not support either of those protocols, TypeError is raised. If the second argument, sentinel , is given, then object must be a callable object. See also Iterator Types. One useful application of the second form of iter is to build a block-reader. For example, reading fixed-width blocks from a binary database file until the end of file is reached:. Return the length the number of items of an object. The argument may be a sequence such as a string, bytes, tuple, list, or range or a collection such as a dictionary, set, or frozen set.

CPython implementation detail: len raises OverflowError on lengths larger than sys. Rather than being a function, list is actually a mutable sequence type, as documented in Lists and Sequence Types — list, tuple, range. Update and return a dictionary representing the current local symbol table.

Free variables are returned by locals when it is called in function blocks, but not in class blocks. Note that at the module level, locals and globals are the same dictionary. The contents of this dictionary should not be modified; changes may not affect the values of local and free variables used by the interpreter.

Return an iterator that applies function to every item of iterable , yielding the results. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel. With multiple iterables, the iterator stops when the shortest iterable is exhausted. For cases where the function inputs are already arranged into argument tuples, see itertools.

If one positional argument is provided, it should be an iterable. The largest item in the iterable is returned. If two or more positional arguments are provided, the largest of the positional arguments is returned. There are two optional keyword-only arguments. The key argument specifies a one-argument ordering function like that used for list. The default argument specifies an object to return if the provided iterable is empty.

If the iterable is empty and default is not provided, a ValueError is raised. If multiple items are maximal, the function returns the first one encountered. See Memory Views for more information. The smallest item in the iterable is returned. If two or more positional arguments are provided, the smallest of the positional arguments is returned.

If multiple items are minimal, the function returns the first one encountered. If default is given, it is returned if the iterator is exhausted, otherwise StopIteration is raised.

Return a new featureless object. It has methods that are common to all instances of Python classes. This function does not accept any arguments. For example:. Open file and return a corresponding file object. If the file cannot be opened, an OSError is raised. See Reading and Writing Files for more examples of how to use this function.

It defaults to 'r' which means open for reading in text mode. Other common values are 'w' for writing truncating the file if it already exists , 'x' for exclusive creation, and 'a' for appending which on some Unix systems, means that all writes append to the end of the file regardless of the current seek position. In text mode, if encoding is not specified the encoding used is platform-dependent: locale. For reading and writing raw bytes use binary mode and leave encoding unspecified.

The available modes are:. The default mode is 'r' open for reading text, a synonym of 'rt'.