或者,实际上,如何按多个键对词典列表进行排序?
我有一个字典列表:
b = [{u'TOT_PTS_Misc': u'Utley, Alex', u'Total_Points': 96.0}, {u'TOT_PTS_Misc': u'Russo, Brandon', u'Total_Points': 96.0}, {u'TOT_PTS_Misc': u'Chappell, Justin', u'Total_Points': 96.0}, {u'TOT_PTS_Misc': u'Foster, Toney', u'Total_Points': 80.0}, {u'TOT_PTS_Misc': u'Lawson, Roman', u'Total_Points': 80.0}, {u'TOT_PTS_Misc': u'Lempke, Sam', u'Total_Points': 80.0}, {u'TOT_PTS_Misc': u'Gnezda, Alex', u'Total_Points': 78.0}, {u'TOT_PTS_Misc': u'Kirks, Damien', u'Total_Points': 78.0}, {u'TOT_PTS_Misc': u'Worden, Tom', u'Total_Points': 78.0}, {u'TOT_PTS_Misc': u'Korecz, Mike', u'Total_Points': 78.0}, {u'TOT_PTS_Misc': u'Swartz, Brian', u'Total_Points': 66.0}, {u'TOT_PTS_Misc': u'Burgess, Randy', u'Total_Points': 66.0}, {u'TOT_PTS_Misc': u'Smugala, Ryan', u'Total_Points': 66.0}, {u'TOT_PTS_Misc': u'Harmon, Gary', u'Total_Points': 66.0}, {u'TOT_PTS_Misc': u'Blasinsky, Scott', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Carter III, Laymon', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Coleman, Johnathan', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Venditti, Nick', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Blackwell, Devon', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Kovach, Alex', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Bolden, Antonio', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Smith, Ryan', u'Total_Points': 60.0}]
并且我需要使用由Total_Points反转的多键排序,然后不由反转TOT_PTS_Misc。
TOT_PTS_Misc
可以在命令提示符下完成,如下所示:
a = sorted(b, key=lambda d: (-d['Total_Points'], d['TOT_PTS_Misc']))
但是我必须通过一个函数来运行它,在其中传递列表和排序键。例如,def multikeysort(dict_list, sortkeys):。
def multikeysort(dict_list, sortkeys):
对于传递给multikeysort函数的任意数量的键,如何使用lambda行将对列表进行排序,并考虑到sortkey可以具有任意数量的键,并且需要识别需要反向排序的键前面加上“-”?
此答案适用于字典中的任何列-否定的列不必是数字。
def multikeysort(items, columns): from operator import itemgetter comparers = [((itemgetter(col[1:].strip()), -1) if col.startswith('-') else (itemgetter(col.strip()), 1)) for col in columns] def comparer(left, right): for fn, mult in comparers: result = cmp(fn(left), fn(right)) if result: return mult * result else: return 0 return sorted(items, cmp=comparer)
您可以这样称呼它:
b = [{u'TOT_PTS_Misc': u'Utley, Alex', u'Total_Points': 96.0}, {u'TOT_PTS_Misc': u'Russo, Brandon', u'Total_Points': 96.0}, {u'TOT_PTS_Misc': u'Chappell, Justin', u'Total_Points': 96.0}, {u'TOT_PTS_Misc': u'Foster, Toney', u'Total_Points': 80.0}, {u'TOT_PTS_Misc': u'Lawson, Roman', u'Total_Points': 80.0}, {u'TOT_PTS_Misc': u'Lempke, Sam', u'Total_Points': 80.0}, {u'TOT_PTS_Misc': u'Gnezda, Alex', u'Total_Points': 78.0}, {u'TOT_PTS_Misc': u'Kirks, Damien', u'Total_Points': 78.0}, {u'TOT_PTS_Misc': u'Worden, Tom', u'Total_Points': 78.0}, {u'TOT_PTS_Misc': u'Korecz, Mike', u'Total_Points': 78.0}, {u'TOT_PTS_Misc': u'Swartz, Brian', u'Total_Points': 66.0}, {u'TOT_PTS_Misc': u'Burgess, Randy', u'Total_Points': 66.0}, {u'TOT_PTS_Misc': u'Smugala, Ryan', u'Total_Points': 66.0}, {u'TOT_PTS_Misc': u'Harmon, Gary', u'Total_Points': 66.0}, {u'TOT_PTS_Misc': u'Blasinsky, Scott', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Carter III, Laymon', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Coleman, Johnathan', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Venditti, Nick', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Blackwell, Devon', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Kovach, Alex', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Bolden, Antonio', u'Total_Points': 60.0}, {u'TOT_PTS_Misc': u'Smith, Ryan', u'Total_Points': 60.0}] a = multikeysort(b, ['-Total_Points', 'TOT_PTS_Misc']) for item in a: print item
尝试对任一列取反。您将看到排序顺序相反。
下一步:对其进行更改,以使其不使用额外的类。
2016-01-17
从这个答案中汲取灵感,从满足条件的可迭代项中获取第一项的最佳方法是什么?,我缩短了代码:
from operator import itemgetter as i def multikeysort(items, columns): comparers = [ ((i(col[1:].strip()), -1) if col.startswith('-') else (i(col.strip()), 1)) for col in columns ] def comparer(left, right): comparer_iter = ( cmp(fn(left), fn(right)) * mult for fn, mult in comparers ) return next((result for result in comparer_iter if result), 0) return sorted(items, cmp=comparer)
如果您喜欢简洁的代码。
2016年1月17日晚
这适用于python3(消除了的cmp参数sort):
cmp
sort
from operator import itemgetter as i from functools import cmp_to_key def cmp(x, y): """ Replacement for built-in function cmp that was removed in Python 3 Compare the two objects x and y and return an integer according to the outcome. The return value is negative if x < y, zero if x == y and strictly positive if x > y. https://portingguide.readthedocs.io/en/latest/comparisons.html#the-cmp-function """ return (x > y) - (x < y) def multikeysort(items, columns): comparers = [ ((i(col[1:].strip()), -1) if col.startswith('-') else (i(col.strip()), 1)) for col in columns ] def comparer(left, right): comparer_iter = ( cmp(fn(left), fn(right)) * mult for fn, mult in comparers ) return next((result for result in comparer_iter if result), 0) return sorted(items, key=cmp_to_key(comparer))
受此答案启发,如何在Python 3中自定义排序?