[Python-checkins] python/dist/src/Doc/lib libstdtypes.tex, 1.167,
1.168
arigo at users.sourceforge.net
arigo at users.sourceforge.net
Thu Nov 4 12:29:11 CET 2004
Update of /cvsroot/python/python/dist/src/Doc/lib
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv3077
Modified Files:
libstdtypes.tex
Log Message:
Mistakes in the "sequence types" page:
* explanation for example with lists of lists made confusing use of
the word "contains" to mean "is built out of".
* wrong formula for slices with step. Is it ok to use LaTeX formulas
(which become images in the html document)? This version needs one
because it's based on a fraction. Just writing "\code{(j-i)/k}" here would
be ambiguous because it looks like a rounding-down-to-the-previous-integer
division, which is not what we need here. Of course we could write
"\code{float(j-i)/k}" but it just looks confusing.
Index: libstdtypes.tex
===================================================================
RCS file: /cvsroot/python/python/dist/src/Doc/lib/libstdtypes.tex,v
retrieving revision 1.167
retrieving revision 1.168
diff -u -d -r1.167 -r1.168
--- libstdtypes.tex 8 Oct 2004 01:52:15 -0000 1.167
+++ libstdtypes.tex 4 Nov 2004 11:29:09 -0000 1.168
@@ -501,10 +501,11 @@
[[3], [3], [3]]
\end{verbatim}
- What has happened is that \code{lists} is a list containing three
- copies of the list \code{[[]]} (a one-element list containing an
- empty list), but the contained list is shared by each copy. You can
- create a list of different lists this way:
+ What has happened is that \code{[[]]} is a one-element list containing
+ an empty list, so all three elements of \code{[[]] * 3} are (pointers to)
+ this single empty list. Modifying any of the elements of \code{lists}
+ modifies this single list. You can create a list of different lists this
+ way:
\begin{verbatim}
>>> lists = [[] for i in range(3)]
@@ -529,8 +530,10 @@
\item[(5)] The slice of \var{s} from \var{i} to \var{j} with step
\var{k} is defined as the sequence of items with index
- \code{\var{x} = \var{i} + \var{n}*\var{k}} such that \code{0}
- \code{<=} \var{n} \code{<} \code{abs(i-j)}. If \var{i} or \var{j}
+ \code{\var{x} = \var{i} + \var{n}*\var{k}} such that
+ $0 \leq n < \frac{j-i}{k}$. In other words, the indices
+ are \code{i}, \code{i+k}, \code{i+2*k}, \code{i+3*k} and so on, stopping when
+ \var{j} is reached (but never including \var{j}). If \var{i} or \var{j}
is greater than \code{len(\var{s})}, use \code{len(\var{s})}. If
\var{i} or \var{j} are omitted then they become ``end'' values
(which end depends on the sign of \var{k}). Note, \var{k} cannot
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