我在Python中有两个列表:
temp1 = ['One', 'Two', 'Three', 'Four']
temp2 = ['One', 'Two']
假设每个列表中的元素都是唯一的,我想用第一个列表中的项创建第三个列表,这些项不在第二个列表中:
temp3 = ['Three', 'Four']
有没有没有周期和检查的快速方法?
我在Python中有两个列表:
temp1 = ['One', 'Two', 'Three', 'Four']
temp2 = ['One', 'Two']
假设每个列表中的元素都是唯一的,我想用第一个列表中的项创建第三个列表,这些项不在第二个列表中:
temp3 = ['Three', 'Four']
有没有没有周期和检查的快速方法?
当前回答
下面是@arkolec的回答,下面是一个用于比较列表、元组和集的实用程序类:
from difflib import SequenceMatcher
class ListDiffer:
def __init__(self, left, right, strict:bool=False):
assert isinstance(left, (list, tuple, set)), "left must be list, tuple or set"
assert isinstance(right, (list, tuple, set)), "right must be list, tuple or set"
self.l = list(left) if isinstance(left, (tuple, set)) else left
self.r = list(right) if isinstance(left, (tuple, set)) else right
if strict:
assert isinstance(left, right.__class__), \
f'left type ({left.__class__.__name__}) must equal right type ({right.__class__.__name__})'
self.diffs = []
self.equal = []
for tag, i, j, k, l in SequenceMatcher(None, self.l, self.r).get_opcodes():
if tag in ['delete', 'replace', 'insert']:
self.diffs.append((tag, i, j, k, l))
elif tag == 'equal':
[self.equal.append(v) for v in left[i:j]]
def has_diffs(self):
return len(self.diffs) > 0
def only_left(self):
a = self.l[:]
[a.remove(v) for v in self.equal]
return a
def only_right(self):
a = self.r[:]
[a.remove(v) for v in self.equal]
return a
def __str__(self, verbose:bool=False):
iD = 0
sb = []
if verbose:
sb.append(f"left: {self.l}\n")
sb.append(f"right: {self.r}\n")
sb.append(f"diffs: ")
for tag, i, j, k, l in self.diffs:
s = f"({iD})"
if iD > 0: sb.append(' | ')
if tag in ('delete', 'replace'): s = f'{s} l:{self.l[i:j]}'
if tag in ('insert', 'replace'): s = f'{s} r:{self.r[k:l]}'
sb.append(s)
iD = iD + 1
if verbose:
sb.append(f"\nequal: {self.equal}")
return ''.join(sb)
def __repr__(self) -> str:
return "<ListDiffer> {}".format(self.__str__())
用法:
left = ['a','b','c']
right = ['aa','b','c','d']
# right = ('aa','b','c','d')
ld = ListDiffer(left, right, strict=True)
print(f'ld.has_diffs(): {ld.has_diffs()}')
print(f'ld: {ld}')
print(f'ld.only_left(): {ld.only_left()}')
print(f'ld.only_right(): {ld.only_right()}')
输出:
ld.has_diffs(): True
ld: (0) l:['a'] r:['aa'] | (1) r:['d']
ld.only_left(): ['a']
ld.only_right(): ['aa', 'd']
我不能说性能,但你可以使用ld.only_left()来获得你正在寻找的结果。
其他回答
可以使用python的XOR运算符来完成。
这将删除每个列表中的重复项 这将显示temp1与temp2和temp2与temp1的差异。
set(temp1) ^ set(temp2)
如果你遇到TypeError: unhashable type: 'list',你需要将列表或集转换为元组。
set(map(tuple, list_of_lists1)).symmetric_difference(set(map(tuple, list_of_lists2)))
参见如何比较python中的列表/集列表?
以下是@SuperNova的回答的修改版本
def get_diff(a: list, b: list) -> list:
return list(set(a) ^ set(b))
我想要一个能够使用两个列表并能做diff in bash所做的事情的东西。因为当你搜索“python diff two lists”时,这个问题首先会弹出,而且不是很具体,所以我会把我想到的贴出来。
使用difflib中的SequenceMather,你可以像diff一样比较两个列表。其他答案都不会告诉你差异发生的位置,但这个答案可以。有些答案只给出了一个方向上的差异。有些元素会重新排序。有些公司不处理副本。但是这个解决方案让你在两个列表之间有了真正的区别:
a = 'A quick fox jumps the lazy dog'.split()
b = 'A quick brown mouse jumps over the dog'.split()
from difflib import SequenceMatcher
for tag, i, j, k, l in SequenceMatcher(None, a, b).get_opcodes():
if tag == 'equal': print('both have', a[i:j])
if tag in ('delete', 'replace'): print(' 1st has', a[i:j])
if tag in ('insert', 'replace'): print(' 2nd has', b[k:l])
这个输出:
both have ['A', 'quick']
1st has ['fox']
2nd has ['brown', 'mouse']
both have ['jumps']
2nd has ['over']
both have ['the']
1st has ['lazy']
both have ['dog']
当然,如果您的应用程序做出了与其他答案相同的假设,那么您将从中受益最大。但如果你正在寻找一个真正的差异功能,那么这是唯一的方法。
例如,其他答案都无法处理:
a = [1,2,3,4,5]
b = [5,4,3,2,1]
但这一个有:
2nd has [5, 4, 3, 2]
both have [1]
1st has [2, 3, 4, 5]
如果散差表的元素是排序和集合的,你可以使用朴素方法。
list1=[1,2,3,4,5]
list2=[1,2,3]
print list1[len(list2):]
或者使用本机set方法:
subset=set(list1).difference(list2)
print subset
import timeit
init = 'temp1 = list(range(100)); temp2 = [i * 2 for i in range(50)]'
print "Naive solution: ", timeit.timeit('temp1[len(temp2):]', init, number = 100000)
print "Native set solution: ", timeit.timeit('set(temp1).difference(temp2)', init, number = 100000)
朴素解:0.0787101593292
本机集解决方案:0.998837615564