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

单线版arulmr解决方案

def diff(listA, listB):
    return set(listA) - set(listB) | set(listB) -set(listA)

其他回答

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。

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))

我知道这个问题已经得到了很好的答案,但我希望使用numpy添加以下方法。

temp1 = ['One', 'Two', 'Three', 'Four']
temp2 = ['One', 'Two']

list(np.setdiff1d(temp1,temp2))

['Four', 'Three'] #Output

这是另一个解决方案:

def diff(a, b):
    xa = [i for i in set(a) if i not in b]
    xb = [i for i in set(b) if i not in a]
    return xa + xb

两个列表(例如list1和list2)之间的差异可以使用下面的简单函数找到。

def diff(list1, list2):
    c = set(list1).union(set(list2))  # or c = set(list1) | set(list2)
    d = set(list1).intersection(set(list2))  # or d = set(list1) & set(list2)
    return list(c - d)

or

def diff(list1, list2):
    return list(set(list1).symmetric_difference(set(list2)))  # or return list(set(list1) ^ set(list2))

通过使用上述函数,可以使用diff(temp2, temp1)或diff(temp1, temp2)找到差异。两者都会给出结果['Four', 'Three']。你不需要担心列表的顺序或者先给出哪个列表。

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