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:mod:`array` --- Efficient arrays of numeric values

This module defines an object type which can compactly represent an array of basic values: characters, integers, floating point numbers. Arrays are sequence types and behave very much like lists, except that the type of objects stored in them is constrained. The type is specified at object creation time by using a :dfn:`type code`, which is a single character. The following type codes are defined:

Type code C Type Python Type Minimum size in bytes Notes
'b' signed char int 1  
'B' unsigned char int 1  
'u' Py_UNICODE Unicode character 2 (1)
'h' signed short int 2  
'H' unsigned short int 2  
'i' signed int int 2  
'I' unsigned int int 2  
'l' signed long int 4  
'L' unsigned long int 4  
'q' signed long long int 8 (2)
'Q' unsigned long long int 8 (2)
'f' float float 4  
'd' double float 8  


  1. The 'u' type code corresponds to Python's obsolete unicode character (:c:type:`Py_UNICODE` which is :c:type:`wchar_t`). Depending on the platform, it can be 16 bits or 32 bits.

    'u' will be removed together with the rest of the :c:type:`Py_UNICODE` API.

  2. The 'q' and 'Q' type codes are available only if the platform C compiler used to build Python supports C :c:type:`long long`, or, on Windows, :c:type:`__int64`.

The actual representation of values is determined by the machine architecture (strictly speaking, by the C implementation). The actual size can be accessed through the :attr:`itemsize` attribute.

The module defines the following type:

A new array whose items are restricted by typecode, and initialized from the optional initializer value, which must be a list, a :term:`bytes-like object`, or iterable over elements of the appropriate type.

If given a list or string, the initializer is passed to the new array's :meth:`fromlist`, :meth:`frombytes`, or :meth:`fromunicode` method (see below) to add initial items to the array. Otherwise, the iterable initializer is passed to the :meth:`extend` method.

Array objects support the ordinary sequence operations of indexing, slicing, concatenation, and multiplication. When using slice assignment, the assigned value must be an array object with the same type code; in all other cases, :exc:`TypeError` is raised. Array objects also implement the buffer interface, and may be used wherever :term:`bytes-like object`s are supported.

The following data items and methods are also supported:

When an array object is printed or converted to a string, it is represented as array(typecode, initializer). The initializer is omitted if the array is empty, otherwise it is a string if the typecode is 'u', otherwise it is a list of numbers. The string is guaranteed to be able to be converted back to an array with the same type and value using :func:`eval`, so long as the :func:`array` function has been imported using from array import array. Examples:

array('u', 'hello \u2641')
array('l', [1, 2, 3, 4, 5])
array('d', [1.0, 2.0, 3.14])