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py-day4 python filter函数

Posted on 2019-02-27 11:25 MJ-majun 阅读(...) 评论(...) 编辑 收藏
filter函数:遍历序列中的每个元素,判断每个元素得到布尔值,如果是True则留下

#
例子:条件筛选 name =['m_xiaoli','zhangfei','m_xiaoma','m_wangyun'] ret = [] def test(name): for i in name: if not i.startswith("m"): ret.append(i) return ret print(test(name)) ['zhangfei'] def test1(array): # (最好不要用全局变量,自己定义一个变量如左) for i in array: if not i.startswith("m"): ret.append(i) return ret print(test1(name))

['zhangfei']
# 在写程序时尽量不要把函数写死,
name =['xiaoli_d','zhangfei','xiaoma_d','m_wangyun']
ret = []
def qu_d(n):            # 定义灵活的函数
    return n.endswith('_d')
def qu_m(w):
    return w.startswith('m_')
def test(func,array): for i in array: if not func(i): ret.append(i) return ret ret = test(qu_d,name) ref = [] def test2(func2,array2): for p in array2: if not func2(p): ref.append(p) return ref ref = test2(qu_m,name) print('不是_d结尾的:',ret) print('不是m_开头的:',ref) 不是_d结尾的: ['zhangfei', 'm_wangyun'] 不是m_开头的: ['xiaoli_d', 'zhangfei', 'xiaoma_d']
 #不定义,用lamnda函数也可以
name =['xiaoli_d','zhangfei','xiaoma_d','m_wangyun']
ret = []
def test(func,array):
    for i in array:
        if not func(i):
            ret.append(i)
    return ret
ret = test(lambda i:i.endswith('_d'),name)
print('不是_d结尾的:', ret)

不是_d结尾的: ['zhangfei', 'm_wangyun']

# 终极版 filter函数
name =['xiaoli_d','zhangfei','xiaoma_d','m_wangyun']
ret = []
def test(func,array):
    for i in array:
        if not func(i):
            ret.append(i)
    return ret
ret = filter(lambda i:not i.endswith('_d'),name)
print('不是_d结尾的:',list(ret))

不是_d结尾的: ['zhangfei', 'm_wangyun']