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authorRaymond Hettinger <python@rcn.com>2003-08-16 00:56:40 (GMT)
committerRaymond Hettinger <python@rcn.com>2003-08-16 00:56:40 (GMT)
commit7ceb29e4a51b12b08884bd2b43c6255228bdd5e5 (patch)
tree0d52a4ea03d0590f3547ee8d4eaa6034c655fd2a /Doc
parentee562fc0846f40aa72c2cbb13983ac2882c0b6ee (diff)
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Incorporate documentation suggestions from feedback on comp.lang.python.
* Positive wording for the description of why < and > and = can all be False. * Move to a three column table format that puts long method names side-by-side with their operator equivalents * Mention that KeyError can be raised by Set.pop() and Set.remove(). * Minor tweaks to the examples. Will backport as soon as Fred rebuilds the docs so I can confirm the tables formatted properly
Diffstat (limited to 'Doc')
-rw-r--r--Doc/lib/libsets.tex97
1 files changed, 42 insertions, 55 deletions
diff --git a/Doc/lib/libsets.tex b/Doc/lib/libsets.tex
index 4d87a4f..71b6d3d 100644
--- a/Doc/lib/libsets.tex
+++ b/Doc/lib/libsets.tex
@@ -65,41 +65,31 @@ elements must be known when the constructor is called.
Instances of \class{Set} and \class{ImmutableSet} both provide
the following operations:
-\begin{tableii}{c|l}{code}{Operation}{Result}
- \lineii{len(\var{s})}{cardinality of set \var{s}}
+\begin{tableiii}{c|c|l}{code}{Operation}{Equivalent}{Result}
+ \lineiii{len(\var{s})}{}{cardinality of set \var{s}}
\hline
- \lineii{\var{x} in \var{s}}
+ \lineiii{\var{x} in \var{s}}{}
{test \var{x} for membership in \var{s}}
- \lineii{\var{x} not in \var{s}}
+ \lineiii{\var{x} not in \var{s}}{}
{test \var{x} for non-membership in \var{s}}
- \lineii{\var{s}.issubset(\var{t})}
- {test whether every element in \var{s} is in \var{t};
- \code{\var{s} <= \var{t}} is equivalent}
- \lineii{\var{s}.issuperset(\var{t})}
- {test whether every element in \var{t} is in \var{s};
- \code{\var{s} >= \var{t}} is equivalent}
+ \lineiii{\var{s}.issubset(\var{t})}{\code{\var{s} <= \var{t}}}
+ {test whether every element in \var{s} is in \var{t}}
+ \lineiii{\var{s}.issuperset(\var{t})}{\code{\var{s} >= \var{t}}}
+ {test whether every element in \var{t} is in \var{s}}
\hline
- \lineii{\var{s} | \var{t}}
- {new set with elements from both \var{s} and \var{t}}
- \lineii{\var{s}.union(\var{t})}
+ \lineiii{\var{s}.union(\var{t})}{\var{s} | \var{t}}
{new set with elements from both \var{s} and \var{t}}
- \lineii{\var{s} \&\ \var{t}}
+ \lineiii{\var{s}.intersection(\var{t})}{\var{s} \&\ \var{t}}
{new set with elements common to \var{s} and \var{t}}
- \lineii{\var{s}.intersection(\var{t})}
- {new set with elements common to \var{s} and \var{t}}
- \lineii{\var{s} - \var{t}}
- {new set with elements in \var{s} but not in \var{t}}
- \lineii{\var{s}.difference(\var{t})}
+ \lineiii{\var{s}.difference(\var{t})}{\var{s} - \var{t}}
{new set with elements in \var{s} but not in \var{t}}
- \lineii{\var{s} \^\ \var{t}}
+ \lineiii{\var{s}.symmetric_difference(\var{t})}{\var{s} \^\ \var{t}}
{new set with elements in either \var{s} or \var{t} but not both}
- \lineii{\var{s}.symmetric_difference(\var{t})}
- {new set with elements in either \var{s} or \var{t} but not both}
- \lineii{\var{s}.copy()}
+ \lineiii{\var{s}.copy()}{}
{new set with a shallow copy of \var{s}}
-\end{tableii}
+\end{tableiii}
In addition, both \class{Set} and \class{ImmutableSet}
support set to set comparisons. Two sets are equal if and only if
@@ -112,8 +102,9 @@ superset of the second set (is a superset, but is not equal).
The subset and equality comparisons do not generalize to a complete
ordering function. For example, any two disjoint sets are not equal and
-are not subsets of each other, so \emph{none} of the following are true:
-\code{\var{a}<\var{b}}, \code{\var{a}==\var{b}}, or \code{\var{a}>\var{b}}.
+are not subsets of each other, so \emph{all} of the following return
+\code{False}: \code{\var{a}<\var{b}}, \code{\var{a}==\var{b}}, or
+\code{\var{a}>\var{b}}.
Accordingly, sets do not implement the \method{__cmp__} method.
Since sets only define partial ordering (subset relationships), the output
@@ -122,47 +113,43 @@ of the \method{list.sort()} method is undefined for lists of sets.
The following table lists operations available in \class{ImmutableSet}
but not found in \class{Set}:
-\begin{tableii}{c|l|c}{code}{Operation}{Result}
+\begin{tableii}{c|l}{code}{Operation}{Result}
\lineii{hash(\var{s})}{returns a hash value for \var{s}}
\end{tableii}
The following table lists operations available in \class{Set}
but not found in \class{ImmutableSet}:
-\begin{tableii}{c|l}{code}{Operation}{Result}
- \lineii{\var{s} |= \var{t}}
- {return set \var{s} with elements added from \var{t}}
- \lineii{\var{s}.union_update(\var{t})}
+\begin{tableiii}{c|c|l}{code}{Operation}{Equivalent}{Result}
+ \lineiii{\var{s}.union_update(\var{t})}
+ {\var{s} |= \var{t}}
{return set \var{s} with elements added from \var{t}}
- \lineii{\var{s} \&= \var{t}}
+ \lineiii{\var{s}.intersection_update(\var{t})}
+ {\var{s} \&= \var{t}}
{return set \var{s} keeping only elements also found in \var{t}}
- \lineii{\var{s}.intersection_update(\var{t})}
- {return set \var{s} keeping only elements also found in \var{t}}
- \lineii{\var{s} -= \var{t}}
- {return set \var{s} after removing elements found in \var{t}}
- \lineii{\var{s}.difference_update(\var{t})}
+ \lineiii{\var{s}.difference_update(\var{t})}
+ {\var{s} -= \var{t}}
{return set \var{s} after removing elements found in \var{t}}
- \lineii{\var{s} \textasciicircum= \var{t}}
- {return set \var{s} with elements from \var{s} or \var{t}
- but not both}
- \lineii{\var{s}.symmetric_difference_update(\var{t})}
+ \lineiii{\var{s}.symmetric_difference_update(\var{t})}
+ {\var{s} \textasciicircum= \var{t}}
{return set \var{s} with elements from \var{s} or \var{t}
but not both}
\hline
- \lineii{\var{s}.add(\var{x})}
+ \lineiii{\var{s}.add(\var{x})}{}
{add element \var{x} to set \var{s}}
- \lineii{\var{s}.remove(\var{x})}
- {remove \var{x} from set \var{s}}
- \lineii{\var{s}.discard(\var{x})}
+ \lineiii{\var{s}.remove(\var{x})}{}
+ {remove \var{x} from set \var{s}; raises KeyError if not present}
+ \lineiii{\var{s}.discard(\var{x})}{}
{removes \var{x} from set \var{s} if present}
- \lineii{\var{s}.pop()}
- {remove and return an arbitrary element from \var{s}}
- \lineii{\var{s}.update(\var{t})}
+ \lineiii{\var{s}.pop()}{}
+ {remove and return an arbitrary element from \var{s}; raises
+ KeyError if empty}
+ \lineiii{\var{s}.update(\var{t})}{}
{add elements from \var{t} to set \var{s}}
- \lineii{\var{s}.clear()}
+ \lineiii{\var{s}.clear()}{}
{remove all elements from set \var{s}}
-\end{tableii}
+\end{tableiii}
\subsection{Example \label{set-example}}
@@ -171,11 +158,11 @@ but not found in \class{ImmutableSet}:
>>> from sets import Set
>>> engineers = Set(['John', 'Jane', 'Jack', 'Janice'])
>>> programmers = Set(['Jack', 'Sam', 'Susan', 'Janice'])
->>> management = Set(['Jane', 'Jack', 'Susan', 'Zack'])
->>> employees = engineers | programmers | management # union
->>> engineering_management = engineers & programmers # intersection
->>> fulltime_management = management - engineers - programmers # difference
->>> engineers.add('Marvin') # add element
+>>> managers = Set(['Jane', 'Jack', 'Susan', 'Zack'])
+>>> employees = engineers | programmers | managers # union
+>>> engineering_management = engineers & managers # intersection
+>>> fulltime_management = managers - engineers - programmers # difference
+>>> engineers.add('Marvin') # add element
>>> print engineers
Set(['Jane', 'Marvin', 'Janice', 'John', 'Jack'])
>>> employees.issuperset(engineers) # superset test