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-rw-r--r--Doc/howto/sorting.rst42
1 files changed, 24 insertions, 18 deletions
diff --git a/Doc/howto/sorting.rst b/Doc/howto/sorting.rst
index 0334b26..b90b61b 100644
--- a/Doc/howto/sorting.rst
+++ b/Doc/howto/sorting.rst
@@ -58,28 +58,28 @@ A common pattern is to sort complex objects using some of the object's indices
as keys. For example:
>>> student_tuples = [
- ('john', 'A', 15),
- ('jane', 'B', 12),
- ('dave', 'B', 10),
- ]
+ ... ('john', 'A', 15),
+ ... ('jane', 'B', 12),
+ ... ('dave', 'B', 10),
+ ... ]
>>> sorted(student_tuples, key=lambda student: student[2]) # sort by age
[('dave', 'B', 10), ('jane', 'B', 12), ('john', 'A', 15)]
The same technique works for objects with named attributes. For example:
>>> class Student:
- def __init__(self, name, grade, age):
- self.name = name
- self.grade = grade
- self.age = age
- def __repr__(self):
- return repr((self.name, self.grade, self.age))
+ ... def __init__(self, name, grade, age):
+ ... self.name = name
+ ... self.grade = grade
+ ... self.age = age
+ ... def __repr__(self):
+ ... return repr((self.name, self.grade, self.age))
>>> student_objects = [
- Student('john', 'A', 15),
- Student('jane', 'B', 12),
- Student('dave', 'B', 10),
- ]
+ ... Student('john', 'A', 15),
+ ... Student('jane', 'B', 12),
+ ... Student('dave', 'B', 10),
+ ... ]
>>> sorted(student_objects, key=lambda student: student.age) # sort by age
[('dave', 'B', 10), ('jane', 'B', 12), ('john', 'A', 15)]
@@ -208,15 +208,15 @@ return a negative value for less-than, return zero if they are equal, or return
a positive value for greater-than. For example, we can do:
>>> def numeric_compare(x, y):
- return x - y
- >>> sorted([5, 2, 4, 1, 3], cmp=numeric_compare)
+ ... return x - y
+ >>> sorted([5, 2, 4, 1, 3], cmp=numeric_compare) # doctest: +SKIP
[1, 2, 3, 4, 5]
Or you can reverse the order of comparison with:
>>> def reverse_numeric(x, y):
- return y - x
- >>> sorted([5, 2, 4, 1, 3], cmp=reverse_numeric)
+ ... return y - x
+ >>> sorted([5, 2, 4, 1, 3], cmp=reverse_numeric) # doctest: +SKIP
[5, 4, 3, 2, 1]
When porting code from Python 2.x to 3.x, the situation can arise when you have
@@ -244,6 +244,12 @@ function. The following wrapper makes that easy to do::
To convert to a key function, just wrap the old comparison function:
+.. testsetup::
+
+ from functools import cmp_to_key
+
+.. doctest::
+
>>> sorted([5, 2, 4, 1, 3], key=cmp_to_key(reverse_numeric))
[5, 4, 3, 2, 1]