diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/faq/programming.rst | 2 | ||||
| -rw-r--r-- | Doc/library/stdtypes.rst | 15 |
2 files changed, 11 insertions, 6 deletions
diff --git a/Doc/faq/programming.rst b/Doc/faq/programming.rst index 2d3cb1c..67a9c56 100644 --- a/Doc/faq/programming.rst +++ b/Doc/faq/programming.rst @@ -1164,6 +1164,8 @@ analogue of lisp car is ``lisp_list[0]`` and the analogue of cdr is usually a lot slower than using Python lists. +.. _faq-multidimensional-list: + How do I create a multidimensional list? ---------------------------------------- diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst index 8573416..b3c9e23 100644 --- a/Doc/library/stdtypes.rst +++ b/Doc/library/stdtypes.rst @@ -854,8 +854,8 @@ operations have the same priority as the corresponding numeric operations. | ``s + t`` | the concatenation of *s* and | (6)(7) | | | *t* | | +--------------------------+--------------------------------+----------+ -| ``s * n`` or | *n* shallow copies of *s* | (2)(7) | -| ``n * s`` | concatenated | | +| ``s * n`` or | equivalent to adding *s* to | (2)(7) | +| ``n * s`` | itself *n* times | | +--------------------------+--------------------------------+----------+ | ``s[i]`` | *i*\ th item of *s*, origin 0 | \(3) | +--------------------------+--------------------------------+----------+ @@ -897,9 +897,9 @@ Notes: (2) Values of *n* less than ``0`` are treated as ``0`` (which yields an empty - sequence of the same type as *s*). Note also that the copies are shallow; - nested structures are not copied. This often haunts new Python programmers; - consider:: + sequence of the same type as *s*). Note that items in the sequence *s* + are not copied; they are referenced multiple times. This often haunts + new Python programmers; consider:: >>> lists = [[]] * 3 >>> lists @@ -909,7 +909,7 @@ Notes: [[3], [3], [3]] What has happened is that ``[[]]`` is a one-element list containing an empty - list, so all three elements of ``[[]] * 3`` are (pointers to) this single empty + list, so all three elements of ``[[]] * 3`` are references to this single empty list. Modifying any of the elements of ``lists`` modifies this single list. You can create a list of different lists this way:: @@ -920,6 +920,9 @@ Notes: >>> lists [[3], [5], [7]] + Further explanation is available in the FAQ entry + :ref:`faq-multidimensional-list`. + (3) If *i* or *j* is negative, the index is relative to the end of the string: ``len(s) + i`` or ``len(s) + j`` is substituted. But note that ``-0`` is |