Mercurial > cpython-lru_cache-weakref

annotate Doc/libarray.tex @ 1471:2ec96140a36b legacy-trunk

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Restructured library documentation
author Guido van Rossum <guido@python.org>
date Sun, 02 Jan 1994 01:22:07 +0000
parents
children 907605320a5f
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
1 \section{Built-in module \sectcode{array}}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
2 \bimodindex{array}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
3 \index{arrays}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
4
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
5 This module defines a new object type which can efficiently represent
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
6 an array of basic values: characters, integers, floating point
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
7 numbers. Arrays are sequence types and behave very much like lists,
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
8 except that the type of objects stored in them is constrained. The
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
9 type is specified at object creation time by using a \dfn{type code},
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
10 which is a single character. The following type codes are defined:
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
11
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
12 \begin{tableiii}{|c|c|c|}{code}{Typecode}{Type}{Minimal size in bytes}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
13 \lineiii{'c'}{character}{1}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
14 \lineiii{'b'}{signed integer}{1}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
15 \lineiii{'h'}{signed integer}{2}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
16 \lineiii{'i'}{signed integer}{2}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
17 \lineiii{'l'}{signed integer}{4}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
18 \lineiii{'f'}{floating point}{4}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
19 \lineiii{'d'}{floating point}{8}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
20 \end{tableiii}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
21
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
22 The actual representation of values is determined by the machine
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
23 architecture (strictly spoken, by the C implementation). The actual
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
24 size can be accessed through the \var{typecode} attribute.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
25
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
26 The module defines the following function:
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
27
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
28 \renewcommand{\indexsubitem}{(in module array)}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
29
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
30 \begin{funcdesc}{array}{typecode\, initializer}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
31 Return a new array whose items are restricted by \var{typecode}, and
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
32 initialized from the optional \var{initializer} value, which must be a
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
33 list or a string. The list or string is passed to the new array's
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
34 \code{fromlist()} or \code{fromstring()} method (see below) to add
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
35 initial items to the array.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
36 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
37
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
38 Array objects support the following data items and methods:
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
39
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
40 \begin{datadesc}{typecode}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
41 The typecode character used to create the array.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
42 \end{datadesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
43
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
44 \begin{datadesc}{itemsize}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
45 The length in bytes of one array item in the internal representation.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
46 \end{datadesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
47
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
48 \begin{funcdesc}{append}{x}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
49 Append a new item with value \var{x} to the end of the array.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
50 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
51
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
52 \begin{funcdesc}{byteswap}{x}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
53 ``Byteswap'' all items of the array. This is only supported for
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
54 integer values. It is useful when reading data ffrom a file written
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
55 on a machine with a different byte order.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
56 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
57
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
58 \begin{funcdesc}{fromfile}{f\, n}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
59 Read \var{n} items (as machine values) from the file object \var{f}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
60 and append them to the end of the array. If less than \var{n} items
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
61 are available, \code{EOFError} is raised, but the items that were
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
62 available are still inserted into the array.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
63 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
64
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
65 \begin{funcdesc}{fromlist}{list}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
66 Appends items from the list. This is equivalent to
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
67 \code{for x in \var{list}: a.append(x)}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
68 except that if there is a type error, the array is unchanged.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
69 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
70
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
71 \begin{funcdesc}{fromstring}{s}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
72 Appends items from the string, interpreting the string as an
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
73 array of machine values (i.e. as if it had been read from a
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
74 file using the \code{fromfile()} method).
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
75 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
76
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
77 \begin{funcdesc}{insert}{i\, x}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
78 Insert a new item with value \var{x} in the array before position
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
79 \var{i}.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
80 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
81
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
82 \begin{funcdesc}{tofile}{f}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
83 Write all items (as machine values) to the file object \var{f}.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
84 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
85
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
86 \begin{funcdesc}{tolist}{}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
87 Convert the array to an ordinary list with the same items.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
88 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
89
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
90 \begin{funcdesc}{tostring}{}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
91 Convert the array to an array of machine values and return the
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
92 string representation (the same sequence of bytes that would
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
93 be written to a file by the \code{tofile()} method.)
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
94 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
95
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
96 When an array object is printed or converted to a string, it is
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
97 represented as \code{array(\var{typecode}, \var{initializer})}. The
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
98 \var{initializer} is omitted if the array is empty, otherwise it is a
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
99 string if the \var{typecode} is \code{'c'}, otherwise it is a list of
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
100 numbers. The string is guaranteed to be able to be converted back to
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
101 an array with the same type and value using reverse quotes
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
102 (\code{``}). Examples:
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
103
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
104 \bcode\begin{verbatim}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
105 array('l')
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
106 array('c', 'hello world')
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
107 array('l', [1, 2, 3, 4, 5])
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
108 array('d', [1.0, 2.0, 3.14])
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
109 \end{verbatim}\ecode