Question

是否有更有效/更优雅的方式来编写函数＆＃39; equal＆＃39;？

def equal(v,u):
  if not v.D==u.D:
    return False 
  if v.f=={} or u.f=={}:
    if not sum(v.f.values())==sum(u.f.values()):
      return False
    else:
      return True
  if not v.f.keys()==u.f.keys():
    if not sum(v.f.values())+sum(u.f.values())==0:
      return False    
  if not sum(v.f.values())==sum(u.f.values()):
     return False
  if not v.D==u.D:
    return False   
  return True

这是预期的输出：

>>> Vec({'a', 'b', 'c'}, {'a':0}) == Vec({'a', 'b', 'c'}, {'b':0})
True
>>> Vec({'a', 'b', 'c'}, {'a': 0}) == Vec({'a', 'b', 'c'}, {})
True
>>> Vec({'a', 'b', 'c'}, {}) == Vec({'a', 'b', 'c'}, {'a': 0})
True

请确保equal(u, v)检查来自u.f和v.f的所有密钥的均等性，即使u.f中v.f中的某些密钥不存在（或>>> Vec({'x','y','z'},{'y':1,'x':2}) == Vec({'x','y','z'},{'y':1,'z':0}) False >>> Vec({'a','b','c'}, {'a':0,'c':1}) == Vec({'a','b','c'}, {'a':0,'c':1,'b':4}) False >>> Vec({'a','b','c'}, {'a':0,'c':1,'b':4}) == Vec({'a','b','c'}, {'a':0,'c':1}) False # The keys matter: >>> Vec({'a','b'},{'a':1}) == Vec({'a','b'},{'b':1}) False # The values matter: >>> Vec({'a','b'},{'a':1}) == Vec({'a','b'},{'a':2}) False """亦然）

Vec

以下是class Vec: """ A vector has two fields: D - the domain (a set) f - a dictionary mapping (some) domain elements to field elements elements of D not appearing in f are implicitly mapped to zero """ def __init__(self, labels, function): self.D = labels self.f = function类：

INSERT INTO table2
          (Name, Company, ProductName, Status, cron_modified_date, count)
    SELECT Name, Company, ProductName, Status, created_date, 1
        FROM table1
    ON DUPLICATE KEY UPDATE
        count = count + 1
        cron_modified_date = created_date;

Answer 1

您似乎想要做的是，如果属性D相等且f相等，排除值为0的条目，则将向量定义为相等。这就是你如何做到的。

def equal(v, u):

    # We will remove the entries with value zero for comparison
    non_zero_v_f = {key: val for key, val in v.f.items() if val != 0}
    non_zero_u_f = {key: val for key, val in u.f.items() if val != 0}

    return v.D == u.D and non_zero_v_f  == non_zero_u_f

此外，您可以将其设为特殊的类方法，以便==实际上将其用于相等。

class Vec:
    def __init__(self, labels, function):

        self.D = labels
        self.f = function

    def __eq__(v, u):

        non_zero_v_f = {key: val for key, val in v.f.items() if val != 0}
        non_zero_u_f = {key: val for key, val in u.f.items() if val != 0}

        return v.D == u.D and non_zero_v_f  == non_zero_u_f

是否有一种pythonic方法在2个向量字典之间编写这个相等的函数？

1 个答案: