[python]dict sort by key or value

熊熊忘記該怎麼 sort by value，查了一下網路記下來。

• http://www.saltycrane.com/blog/2007/09/how-to-sort-python-dictionary-by-keys/

for key in sorted(mydict.iterkeys()):
    print "%s: %s" % (key, mydict[key])

 

for key, value in sorted(mydict.iteritems(), key=lambda (k,v): (v,k)):
    print "%s: %s" % (key, value)

 

• http://code.activestate.com/recipes/52306-to-sort-a-dictionary/

# (IMHO) the simplest approach:
def sortedDictValues1(adict):
    items = adict.items()
    items.sort()
    return [value for key, value in items]

# an alternative implementation, which
# happens to run a bit faster for large
# dictionaries on my machine:
def sortedDictValues2(adict):
    keys = adict.keys()
    keys.sort()
    return [dict[key] for key in keys]

# a further slight speed-up on my box
# is to map a bound-method:
def sortedDictValues3(adict):
    keys = adict.keys()
    keys.sort()
    return map(adict.get, keys)

 

• http://falldog7.blogspot.com/2009/10/python-dictionary-or-classitemlistsort.html

d= [ {'id':0, 'value':9}, {'id':1, 'value':100}, {'id':5, 'value':99}, {'id':3, 'value':19}, {'id':2, 'value':59} ]
d.sort(key=lambda x:x['id']) #針對key 'id' 做sort
d.sort(key=lambda x:x['value']) #針對key 'value' 做sort

#以下用cmp，可以達到上面指定key的效果
d.sort(cmp=lambda x,y: cmp(x['id'], y['id']))
d.sort(cmp=lambda x,y: cmp(x['value'], y['value']))

 

class data:
    def __init__(self, _id, _value):
        self.id    = _id
        self.value = _value
c = [ data(0,9), data(1,100), data(5,99), data(3,19), data(2,59) ]
c.sort(key=lambda x:x.id)#針對class member id 做sort
c.sort(key=lambda x:x.value)#針對class member value 做sort

#以下用cmp，可以達到上面指定key的效果
c.sort(cmp=lambda x,y: cmp(x.id, y.id) )
c.sort(cmp=lambda x,y: cmp(x.value, y.value))