Added complex numbers (AMK).
Clarify that sort() works in-place. Renamed dict.absorb() to dict.update().
This commit is contained in:
Guido van Rossum
parent
a8d5131d57
commit
3a0d850160
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@ -143,8 +143,9 @@ Two more operations with the same syntactic priority, \code{in} and
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\subsection{Numeric Types}
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There are three numeric types: \dfn{plain integers}, \dfn{long integers}, and
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\dfn{floating point numbers}. Plain integers (also just called \dfn{integers})
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There are four numeric types: \dfn{plain integers}, \dfn{long integers},
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\dfn{floating point numbers}, and \dfn{complex numbers}.
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Plain integers (also just called \dfn{integers})
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are implemented using \code{long} in \C{}, which gives them at least 32
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bits of precision. Long integers have unlimited precision. Floating
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point numbers are implemented using \code{double} in \C{}. All bets on
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@ -155,35 +156,45 @@ working with.
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\indexii{integer}{type}
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\indexiii{long}{integer}{type}
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\indexii{floating point}{type}
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\indexii{complex number}{type}
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\indexii{\C{}}{language}
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Complex numbers have a real and imaginary part, which are both
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implemented using \code{double} in \C{}. To extract these parts from
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a complex number \code{z}, use \code{z.real} and \code{z.imag}.
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Numbers are created by numeric literals or as the result of built-in
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functions and operators. Unadorned integer literals (including hex
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and octal numbers) yield plain integers. Integer literals with an \samp{L}
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or \samp{l} suffix yield long integers
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(\samp{L} is preferred because \code{1l} looks too much like eleven!).
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Numeric literals containing a decimal point or an exponent sign yield
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floating point numbers.
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floating point numbers. Appending \code{j} or \code{J} to a numeric
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literal yields a complex number.
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\indexii{numeric}{literals}
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\indexii{integer}{literals}
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\indexiii{long}{integer}{literals}
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\indexii{floating point}{literals}
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\indexii{complex number}{literals}
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\indexii{hexadecimal}{literals}
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\indexii{octal}{literals}
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Python fully supports mixed arithmetic: when a binary arithmetic
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operator has operands of different numeric types, the operand with the
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``smaller'' type is converted to that of the other, where plain
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integer is smaller than long integer is smaller than floating point.
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integer is smaller than long integer is smaller than floating point is
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smaller than complex.
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Comparisons between numbers of mixed type use the same rule.%
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\footnote{As a consequence, the list \code{[1, 2]} is considered equal
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to \code{[1.0, 2.0]}, and similar for tuples.}
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The functions \code{int()}, \code{long()} and \code{float()} can be used
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The functions \code{int()}, \code{long()}, \code{float()},
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and \code{complex()} can be used
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to coerce numbers to a specific type.
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\index{arithmetic}
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\bifuncindex{int}
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\bifuncindex{long}
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\bifuncindex{float}
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\bifuncindex{complex}
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All numeric types support the following operations, sorted by
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ascending priority (operations in the same box have the same
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@ -201,12 +212,14 @@ comparison operations):
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\lineiii{-\var{x}}{\var{x} negated}{}
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\lineiii{+\var{x}}{\var{x} unchanged}{}
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\hline
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\lineiii{abs(\var{x})}{absolute value of \var{x}}{}
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\lineiii{abs(\var{x})}{absolute value or magnitude of \var{x}}{}
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\lineiii{int(\var{x})}{\var{x} converted to integer}{(2)}
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\lineiii{long(\var{x})}{\var{x} converted to long integer}{(2)}
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\lineiii{float(\var{x})}{\var{x} converted to floating point}{}
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\lineiii{complex(\var{re},\var{im})}{a complex number with real part \var{re}, imaginary part \var{im}. \var{im} defaults to zero.}{}
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\lineiii{divmod(\var{x}, \var{y})}{the pair \code{(\var{x} / \var{y}, \var{x} \%{} \var{y})}}{(3)}
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\lineiii{pow(\var{x}, \var{y})}{\var{x} to the power \var{y}}{}
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\lineiii{\var{x}**\var{y}}{\var{x} to the power \var{y}}{}
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\end{tableiii}
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\indexiii{operations on}{numeric}{types}
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@ -439,11 +452,9 @@ The following operations are defined on mutable sequence types (where
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\lineiii{\var{s}.remove(\var{x})}
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{same as \code{del \var{s}[\var{s}.index(\var{x})]}}{(1)}
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\lineiii{\var{s}.reverse()}
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{reverses the items of \var{s} in place}{}
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{reverses the items of \var{s} in place}{(3)}
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\lineiii{\var{s}.sort()}
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{permutes the items of \var{s} to satisfy
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\code{\var{s}[\var{i}] <= \var{s}[\var{j}]},
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for \code{\var{i} < \var{j}}}{(2)}
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{sort the items of \var{s} in place}{(2), (3)}
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\end{tableiii}
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\indexiv{operations on}{mutable}{sequence}{types}
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\indexiii{operations on}{sequence}{types}
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@ -474,6 +485,12 @@ Notes:
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to use calls to \code{sort()} and \code{reverse()} than to use
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\code{sort()} with a comparison function that reverses the ordering of
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the elements.
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\item[(3)] The \code{sort()} and \code{reverse()} methods modify the
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list in place for economy of space when sorting or reversing a large
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list. They don't return the sorted or reversed list to remind you of
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this side effect.
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\end{description}
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\subsection{Mapping Types}
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@ -504,12 +521,12 @@ mapping, \var{k} is a key and \var{x} is an arbitrary object):
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\lineiii{\var{a}[\var{k}]}{the item of \var{a} with key \var{k}}{(1)}
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\lineiii{\var{a}[\var{k}] = \var{x}}{set \code{\var{a}[\var{k}]} to \var{x}}{}
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\lineiii{del \var{a}[\var{k}]}{remove \code{\var{a}[\var{k}]} from \var{a}}{(1)}
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\lineiii{\var{a}.absorb(b)}{\code{for k, v in b.items(): a[k] = v}}{(3)}
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\lineiii{\var{a}.clear()}{remove all items from \code{a}}{}
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\lineiii{\var{a}.copy()}{a (shallow) copy of \code{a}}{}
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\lineiii{\var{a}.has_key(\var{k})}{\code{1} if \var{a} has a key \var{k}, else \code{0}}{}
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\lineiii{\var{a}.items()}{a copy of \var{a}'s list of (key, item) pairs}{(2)}
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\lineiii{\var{a}.keys()}{a copy of \var{a}'s list of keys}{(2)}
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\lineiii{\var{a}.update(b)}{\code{for k, v in b.items(): a[k] = v}}{(3)}
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\lineiii{\var{a}.values()}{a copy of \var{a}'s list of values}{(2)}
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\end{tableiii}
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\indexiii{operations on}{mapping}{types}
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@ -143,8 +143,9 @@ Two more operations with the same syntactic priority, \code{in} and
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\subsection{Numeric Types}
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There are three numeric types: \dfn{plain integers}, \dfn{long integers}, and
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\dfn{floating point numbers}. Plain integers (also just called \dfn{integers})
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There are four numeric types: \dfn{plain integers}, \dfn{long integers},
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\dfn{floating point numbers}, and \dfn{complex numbers}.
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Plain integers (also just called \dfn{integers})
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are implemented using \code{long} in \C{}, which gives them at least 32
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bits of precision. Long integers have unlimited precision. Floating
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point numbers are implemented using \code{double} in \C{}. All bets on
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@ -155,35 +156,45 @@ working with.
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\indexii{integer}{type}
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\indexiii{long}{integer}{type}
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\indexii{floating point}{type}
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\indexii{complex number}{type}
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\indexii{\C{}}{language}
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Complex numbers have a real and imaginary part, which are both
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implemented using \code{double} in \C{}. To extract these parts from
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a complex number \code{z}, use \code{z.real} and \code{z.imag}.
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Numbers are created by numeric literals or as the result of built-in
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functions and operators. Unadorned integer literals (including hex
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and octal numbers) yield plain integers. Integer literals with an \samp{L}
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or \samp{l} suffix yield long integers
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(\samp{L} is preferred because \code{1l} looks too much like eleven!).
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Numeric literals containing a decimal point or an exponent sign yield
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floating point numbers.
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floating point numbers. Appending \code{j} or \code{J} to a numeric
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literal yields a complex number.
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\indexii{numeric}{literals}
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\indexii{integer}{literals}
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\indexiii{long}{integer}{literals}
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\indexii{floating point}{literals}
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\indexii{complex number}{literals}
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\indexii{hexadecimal}{literals}
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\indexii{octal}{literals}
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Python fully supports mixed arithmetic: when a binary arithmetic
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operator has operands of different numeric types, the operand with the
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``smaller'' type is converted to that of the other, where plain
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integer is smaller than long integer is smaller than floating point.
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integer is smaller than long integer is smaller than floating point is
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smaller than complex.
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Comparisons between numbers of mixed type use the same rule.%
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\footnote{As a consequence, the list \code{[1, 2]} is considered equal
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to \code{[1.0, 2.0]}, and similar for tuples.}
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The functions \code{int()}, \code{long()} and \code{float()} can be used
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The functions \code{int()}, \code{long()}, \code{float()},
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and \code{complex()} can be used
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to coerce numbers to a specific type.
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\index{arithmetic}
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\bifuncindex{int}
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\bifuncindex{long}
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\bifuncindex{float}
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\bifuncindex{complex}
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All numeric types support the following operations, sorted by
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ascending priority (operations in the same box have the same
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@ -201,12 +212,14 @@ comparison operations):
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\lineiii{-\var{x}}{\var{x} negated}{}
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\lineiii{+\var{x}}{\var{x} unchanged}{}
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\hline
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\lineiii{abs(\var{x})}{absolute value of \var{x}}{}
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\lineiii{abs(\var{x})}{absolute value or magnitude of \var{x}}{}
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\lineiii{int(\var{x})}{\var{x} converted to integer}{(2)}
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\lineiii{long(\var{x})}{\var{x} converted to long integer}{(2)}
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\lineiii{float(\var{x})}{\var{x} converted to floating point}{}
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\lineiii{complex(\var{re},\var{im})}{a complex number with real part \var{re}, imaginary part \var{im}. \var{im} defaults to zero.}{}
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\lineiii{divmod(\var{x}, \var{y})}{the pair \code{(\var{x} / \var{y}, \var{x} \%{} \var{y})}}{(3)}
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\lineiii{pow(\var{x}, \var{y})}{\var{x} to the power \var{y}}{}
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\lineiii{\var{x}**\var{y}}{\var{x} to the power \var{y}}{}
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\end{tableiii}
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\indexiii{operations on}{numeric}{types}
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@ -439,11 +452,9 @@ The following operations are defined on mutable sequence types (where
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\lineiii{\var{s}.remove(\var{x})}
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{same as \code{del \var{s}[\var{s}.index(\var{x})]}}{(1)}
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\lineiii{\var{s}.reverse()}
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{reverses the items of \var{s} in place}{}
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{reverses the items of \var{s} in place}{(3)}
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\lineiii{\var{s}.sort()}
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{permutes the items of \var{s} to satisfy
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\code{\var{s}[\var{i}] <= \var{s}[\var{j}]},
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for \code{\var{i} < \var{j}}}{(2)}
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{sort the items of \var{s} in place}{(2), (3)}
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\end{tableiii}
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\indexiv{operations on}{mutable}{sequence}{types}
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\indexiii{operations on}{sequence}{types}
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@ -474,6 +485,12 @@ Notes:
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to use calls to \code{sort()} and \code{reverse()} than to use
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\code{sort()} with a comparison function that reverses the ordering of
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the elements.
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\item[(3)] The \code{sort()} and \code{reverse()} methods modify the
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list in place for economy of space when sorting or reversing a large
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list. They don't return the sorted or reversed list to remind you of
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this side effect.
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\end{description}
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\subsection{Mapping Types}
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@ -504,12 +521,12 @@ mapping, \var{k} is a key and \var{x} is an arbitrary object):
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\lineiii{\var{a}[\var{k}]}{the item of \var{a} with key \var{k}}{(1)}
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\lineiii{\var{a}[\var{k}] = \var{x}}{set \code{\var{a}[\var{k}]} to \var{x}}{}
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\lineiii{del \var{a}[\var{k}]}{remove \code{\var{a}[\var{k}]} from \var{a}}{(1)}
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\lineiii{\var{a}.absorb(b)}{\code{for k, v in b.items(): a[k] = v}}{(3)}
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\lineiii{\var{a}.clear()}{remove all items from \code{a}}{}
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\lineiii{\var{a}.copy()}{a (shallow) copy of \code{a}}{}
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\lineiii{\var{a}.has_key(\var{k})}{\code{1} if \var{a} has a key \var{k}, else \code{0}}{}
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\lineiii{\var{a}.items()}{a copy of \var{a}'s list of (key, item) pairs}{(2)}
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\lineiii{\var{a}.keys()}{a copy of \var{a}'s list of keys}{(2)}
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\lineiii{\var{a}.update(b)}{\code{for k, v in b.items(): a[k] = v}}{(3)}
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\lineiii{\var{a}.values()}{a copy of \var{a}'s list of values}{(2)}
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\end{tableiii}
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\indexiii{operations on}{mapping}{types}
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