Differences between revisions 1 and 5 (spanning 4 versions)

Warning:

Starting from version 9.0, the default distributed version of Sage is using Python 3. See Python3-Switch for more information.

Main caveat

range and xrange

In Python range is a function that returns a list.

   1 sage-8.9: range(5)
   2 [0, 1, 2, 3, 4]
   3 sage-8.9: type(range(5))
   4 <type 'list'>

In Python 3, range is an object that somehow behave as a list (ie elements can still be acessed with square bracket, it has a length, etc) but it is not a list.

   1 sage-9.0: range(5)
   2 range(0, 5)
   3 sage-9.0: range(5)[2]
   4 2
   5 sage-9.0: range(5)[1::2]
   6 range(1, 5, 2)
   7 sage-9.0: type(range(5))
   8 <class 'range'>

The iterator xrange is no longer valid in Python 3 simply use range instead.

strings, unicode and bytes

In Python 2 a chain of characters between simple, double or triple quotes creates an ascii string. To create a unicode string one has to use the prefix u (which remains valid in Python 3).

In Python 3, a chain of characters between quote will gives rise to a unicode string. To create specifically an ascii string one has to use the prefix b (which is already valid in Python 2).

-  ⇤ ← Revision 1 as of 2019-10-31 05:53:22 → 
  Size: 727
  Editor: vdelecroix
  Comment:
+   ← Revision 5 as of 2019-10-31 06:03:24 → ⇥
  Size: 1211
  Editor: vdelecroix
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 7:
-In Python `range` is a function that return a list.
+In Python `range` is a function that returns a list.
 Line 11:
-sage: type(range(5))
+sage-8.9: type(range(5))
 Line 15:
-{{{
+{{{#!highlight python
 Line 20:
-sage: range(5)[1::2]
+sage-9.0: range(5)[1::2]
 Line 22:
-sage: type(range(5))
+sage-9.0: type(range(5))
 Line 26:
-The iterator `xrange` is no longer valid in Python 3.
+The iterator `xrange` is no longer valid in Python 3 simply use `range` instead.

== strings, unicode and bytes ==

In Python 2 a chain of characters between simple, double or triple quotes creates an ascii string. To create a unicode string one has to use the prefix `u` (which remains valid in Python 3).

In Python 3, a chain of characters between quote will gives rise to a unicode string. To create specifically an ascii string one has to use the prefix `b` (which is already valid in Python 2).

Diff for "Python3-user"

Main caveat

range and xrange

strings, unicode and bytes