Mercurial > cpython-lru_cache-weakref
diff Doc/lib/libstdtypes.tex @ 33899:eb979c3f14ba legacy-trunk
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.
| author | Armin Rigo <arigo@tunes.org> |
|---|---|
| date | Thu, 04 Nov 2004 11:29:09 +0000 |
| parents | af300403edb8 |
| children | 023801332395 |
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--- a/Doc/lib/libstdtypes.tex Thu Nov 04 05:45:44 2004 +0000 +++ b/Doc/lib/libstdtypes.tex Thu Nov 04 11:29:09 2004 +0000 @@ -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