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author | Guido van Rossum <guido@python.org> | 1994-01-02 01:22:07 (GMT) |
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committer | Guido van Rossum <guido@python.org> | 1994-01-02 01:22:07 (GMT) |
commit | 5fdeeeae2a12b9956cc84d62eae82f72cabc8664 (patch) | |
tree | ac0053479e10099850c8e0d06e31cb3afbf632bb /Doc/libarray.tex | |
parent | 0b0719866e8a32d0a787e73bca9e79df1d1a74f8 (diff) | |
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Restructured library documentation
Diffstat (limited to 'Doc/libarray.tex')
-rw-r--r-- | Doc/libarray.tex | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/Doc/libarray.tex b/Doc/libarray.tex new file mode 100644 index 0000000..21122f0 --- /dev/null +++ b/Doc/libarray.tex @@ -0,0 +1,109 @@ +\section{Built-in module \sectcode{array}} +\bimodindex{array} +\index{arrays} + +This module defines a new object type which can efficiently 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: + +\begin{tableiii}{|c|c|c|}{code}{Typecode}{Type}{Minimal size in bytes} +\lineiii{'c'}{character}{1} +\lineiii{'b'}{signed integer}{1} +\lineiii{'h'}{signed integer}{2} +\lineiii{'i'}{signed integer}{2} +\lineiii{'l'}{signed integer}{4} +\lineiii{'f'}{floating point}{4} +\lineiii{'d'}{floating point}{8} +\end{tableiii} + +The actual representation of values is determined by the machine +architecture (strictly spoken, by the C implementation). The actual +size can be accessed through the \var{typecode} attribute. + +The module defines the following function: + +\renewcommand{\indexsubitem}{(in module array)} + +\begin{funcdesc}{array}{typecode\, initializer} +Return a new array whose items are restricted by \var{typecode}, and +initialized from the optional \var{initializer} value, which must be a +list or a string. The list or string is passed to the new array's +\code{fromlist()} or \code{fromstring()} method (see below) to add +initial items to the array. +\end{funcdesc} + +Array objects support the following data items and methods: + +\begin{datadesc}{typecode} +The typecode character used to create the array. +\end{datadesc} + +\begin{datadesc}{itemsize} +The length in bytes of one array item in the internal representation. +\end{datadesc} + +\begin{funcdesc}{append}{x} +Append a new item with value \var{x} to the end of the array. +\end{funcdesc} + +\begin{funcdesc}{byteswap}{x} +``Byteswap'' all items of the array. This is only supported for +integer values. It is useful when reading data ffrom a file written +on a machine with a different byte order. +\end{funcdesc} + +\begin{funcdesc}{fromfile}{f\, n} +Read \var{n} items (as machine values) from the file object \var{f} +and append them to the end of the array. If less than \var{n} items +are available, \code{EOFError} is raised, but the items that were +available are still inserted into the array. +\end{funcdesc} + +\begin{funcdesc}{fromlist}{list} +Appends items from the list. This is equivalent to +\code{for x in \var{list}: a.append(x)} +except that if there is a type error, the array is unchanged. +\end{funcdesc} + +\begin{funcdesc}{fromstring}{s} +Appends items from the string, interpreting the string as an +array of machine values (i.e. as if it had been read from a +file using the \code{fromfile()} method). +\end{funcdesc} + +\begin{funcdesc}{insert}{i\, x} +Insert a new item with value \var{x} in the array before position +\var{i}. +\end{funcdesc} + +\begin{funcdesc}{tofile}{f} +Write all items (as machine values) to the file object \var{f}. +\end{funcdesc} + +\begin{funcdesc}{tolist}{} +Convert the array to an ordinary list with the same items. +\end{funcdesc} + +\begin{funcdesc}{tostring}{} +Convert the array to an array of machine values and return the +string representation (the same sequence of bytes that would +be written to a file by the \code{tofile()} method.) +\end{funcdesc} + +When an array object is printed or converted to a string, it is +represented as \code{array(\var{typecode}, \var{initializer})}. The +\var{initializer} is omitted if the array is empty, otherwise it is a +string if the \var{typecode} is \code{'c'}, 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 reverse quotes +(\code{``}). Examples: + +\bcode\begin{verbatim} +array('l') +array('c', 'hello world') +array('l', [1, 2, 3, 4, 5]) +array('d', [1.0, 2.0, 3.14]) +\end{verbatim}\ecode |