# `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, complex numbers. Arrays are mutable 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 type code. The following type codes are defined:

Code d'indication du type | Type C | Type Python | Taille minimum en octets | Notes
--- | --- | --- | --- | ---
`'b'` | `signed char` | int | 1 |
`'B'` | `unsigned char` | int | 1 |
`'w'` | Py_UCS4 | Caractère Unicode | 4 | (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 |
`'Q'` | `unsigned long long` | int | 8 |
`'e'` | _Float16 | float | 2 | (2)
`'f'` | float | float | 4 |
`'d'` | double | float | 8 |
`'Zf'` | float complex | complex | 8 | (3)
`'Zd'` | double complex | complex | 16 | (3)

Notes :

1. Ajouté dans la version 3.13.

2. The IEEE 754 binary16 "half precision" type was introduced in the 2008 revision of the IEEE 754 standard. This type is not widely supported by C compilers. It's available as _Float16 type, if the compiler supports the Annex H of the C23 standard.

   Ajouté dans la version 3.15.

3. Complex types (`Zf` and `Zd`) are available unconditionally, regardless on support for complex types (the Annex G of the C11 standard) by the C compiler. As specified in the C11 standard, each complex type is represented by a two-element C array containing, respectively, the real and imaginary parts.

   Ajouté dans la version 3.15.

Voir aussi

The ctypes and struct modules, as well as third-party modules like numpy, use similar -- but slightly different -- type codes.

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 `array.itemsize` attribute.

The module defines the following item:

array.typecodes

  A tuple with all available type codes.

  Modifié dans la version 3.15: The type changed from `str` to `tuple`.

Le module définit le type suivant :

class array.array(typecode[, initializer])

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

  If given a `bytes` or `bytearray` object, the initializer is passed to the new array's `frombytes()` method; if given a Unicode string, the initializer is passed to the `fromunicode()` method; otherwise, the initializer's iterator is passed to the `extend()` method to add initial items to the array.

  Array objects support the ordinary mutable 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, `TypeError` is raised. Array objects also implement the buffer interface, and may be used wherever bytes-like objects are supported.

  Arrays are generic over the type of their contents.

  Lève un événement d'audit `array.__new__` avec les arguments `typecode`, `initializer`.

  typecode

    Le code (de type Python caractère) utilisé pour spécifier le type des éléments du tableau.

  itemsize

    La longueur en octets d'un élément du tableau dans la représentation interne.

  append(value, /)

    Append a new item with the specified value to the end of the array.

  buffer_info()

    Return a tuple `(address, length)` giving the current memory address and the length in elements of the buffer used to hold array's contents. The size of the memory buffer in bytes can be computed as `array.buffer_info()[1] * array.itemsize`. This is occasionally useful when working with low-level (and inherently unsafe) I/O interfaces that require memory addresses, such as certain `ioctl()` operations. The returned numbers are valid as long as the array exists and no length-changing operations are applied to it.

    Note

    Lors de l'utilisation d'objets tableaux provenant de codes écrits en C ou C++ (le seul moyen d'utiliser efficacement ces informations), il est plus logique d'utiliser l'interface tampon supportée par les objets tableaux. Cette méthode est maintenue pour des raisons de rétrocompatibilité et devrait être évitée dans un nouveau code. L'interface tampon est documentée dans Protocole tampon.

  byteswap()

    "Byteswap" all items of the array. This is only supported for values which are 1, 2, 4, 8 or 16 bytes in size; for other types of values, `RuntimeError` is raised. It is useful when reading data from a file written on a machine with a different byte order. Note, that for complex types the order of components (the real part, followed by imaginary part) is preserved.

  count(value, /)

    Return the number of occurrences of value in the array.

  extend(iterable, /)

    Ajoute les éléments de iterable à la fin du tableau. Si iterable est un autre tableau, il doit le même code d'indication du type ; dans le cas contraire, `TypeError` sera levée. Si iterable n'est pas un tableau, il doit être itérable et ces éléments doivent être du bon type pour être ajoutés dans le tableau.

  frombytes(buffer, /)

    Appends items from the bytes-like object, interpreting its content as an array of machine values (as if it had been read from a file using the `fromfile()` method).

    Ajouté dans la version 3.2: `fromstring()` is renamed to `frombytes()` for clarity.

  fromfile(f, n, /)

    Read n items (as machine values) from the file object f and append them to the end of the array. If less than n items are available, `EOFError` is raised, but the items that were available are still inserted into the array.

  fromlist(list, /)

    Ajoute les éléments de la liste. C'est l'équivalent de `for x in list: a.append(x)` sauf que s'il y a une erreur de type, le tableau est inchangé.

  fromunicode(ustr, /)

    Extends this array with data from the given Unicode string. The array must have type code `'w'`; otherwise a `ValueError` is raised. Use `array.frombytes(unicodestring.encode(enc))` to append Unicode data to an array of some other type.

  index(value[, start[, stop]])

    Return the smallest i such that i is the index of the first occurrence of value in the array. The optional arguments start and stop can be specified to search for value within a subsection of the array. Raise `ValueError` if value is not found.

    Modifié dans la version 3.10: Added optional start and stop parameters.

  insert(index, value, /)

    Insert a new item value in the array before position index. Negative values are treated as being relative to the end of the array.

  pop(index=-1, /)

    Supprime l'élément du tableau avec l'index i et le renvoie. L'argument optionnel par défaut est à `-1`, de sorte que par défaut le dernier élément est supprimé et renvoyé.

  remove(value, /)

    Remove the first occurrence of value from the array.

  clear()

    Remove all elements from the array.

    Ajouté dans la version 3.13.

  reverse()

    Inverse l'ordre des éléments du tableau.

  tobytes()

    Convertit le tableau en un tableau de valeurs machine et renvoie la représentation en octets (la même séquence d'octets qui serait écrite par la méthode `tofile()`).

    Ajouté dans la version 3.2: `tostring()` is renamed to `tobytes()` for clarity.

  tofile(f, /)

    Écrit tous les éléments (en tant que valeurs machine) du file object f.

  tolist()

    Convertit le tableau en une liste ordinaire avec les mêmes éléments.

  tounicode()

    Convert the array to a Unicode string. The array must have a type `'w'`; otherwise a `ValueError` is raised. Use `array.tobytes().decode(enc)` to obtain a Unicode string from an array of some other type.

The string representation of array objects has the form `array(typecode, initializer)`. The initializer is omitted if the array is empty, otherwise it is a Unicode string if the typecode is `'w'`, otherwise it is a list of numbers. The string representation is guaranteed to be able to be converted back to an array with the same type and value using `eval()`, so long as the `array` class has been imported using `from array import array`. Variables `inf` and `nan` must also be defined if it contains corresponding floating-point values. Examples:

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

Voir aussi

Module `struct`

  Empaquetage et dépaquetage de données binaires hétérogènes.

NumPy

  The NumPy package defines another array type.